I had the same issue, card was fine for months, then it kept on disappearing. A reboot would fix the problem, but it kept on recurring. I bit the bullet, and rescued the card data while I could, then reformatted. It 'seems' stable at present, but I am past trusting the Moto G3 with my SD card data. I considered doing a factory reset, and just saying no to the Marshmallow update, but I will see how it goes. If you want to try reusing the card, try SDFormater from "https://www.sdcard.org/downloads/formatter_4/" , it might be able to see your card to format it. No guarantees though.

I also have an issue with the MTP device driver in Windows constantly failing to initialize, and the Moto G showing in Windows, but not showing the card, just an empty folder. Don't hold your breath waiting for Lenovo to offer any assistance. They already have your money.

I'm also having this problem. I know  I should have backed up and I am willing to buy another card but it really makws me very angrey that so many people are having this problem and it is not beoiing addressed. From a phone that I really loved this is now becoming a phone that I do not like at all! 

If I get another SD card I will nott use it as internal storage. Fortunately I have the 16GB model so I can probably run all my apps from my phone BUT I should not have to. GRRRRR

I've had same problems with Moto 3rd Gen, and it just happened for the 3rd time in 3 months. I don't have a solution but thought I'd highlite my experience.

NOV 2015 Consumer Cellular supplied Moto 3rd Gen with Lollipop. I tried SanDisk 32G Class 10 and phone
wouldn't recognize that or any card. But that and other cards worked in a older HUAWEI. I read that Lollipop
had problems with SD cards. Decided to wait for Marshmellow release.

FEB 2016 I updated the Moto 3rd Gen with Marshmellow, and still had the problem. Saw some reviews
indicating Moto 3rd Gen had electrical connector problems with SD card slots so I asked Consumer Cellular
for replacement.

MAR 2016 Consumer Cellular replaced the phone with a new one and the SD card worked! I formated
SanDisk 32G Class 10 as internal and used for all photos and some apps.

After a rew weeks of everything working well, phone message SD card not working and should Forget. I did
not select forget several times, and SD card became unrecognizable. Eventually lost all data, and SD card is
totally unusable; Can't even format SD card on phone or PC.

JUN 21, 2016 Received new SanDisk 32G Class 10 from Amazon and installed and formated as Internal.
Moved all recent pictures and a few apps.

JULY 5 2016 Again, all of a sudden, message SD card not working and should Forget. I selected Forget, lost all
my pictures, but was able to reused the card a portable storage.

I'm beginning to believe that the problem is with Android Marshmellow, Consumer Cellular patches, or Moto
3rd Gen device. Also, I just read that the Instagram App can cause problems with SD cards. That app just
updated on my phone in the last 24 hours.

I'm planning to test a Moto 3rd Gen that was purchased directly from Amazon to see if I can start to bracket the
likely caueses.

---

wrote:

I've had same problems with Moto 3rd Gen, and it just happened for the 3rd time in 3 months. I don't have a solution but thought I'd highlite my experience.

NOV 2015 Consumer Cellular supplied Moto 3rd Gen with Lollipop. I tried SanDisk 32G Class 10 and phone
wouldn't recognize that or any card. But that and other cards worked in a older HUAWEI. I read that Lollipop
had problems with SD cards. Decided to wait for Marshmellow release.

FEB 2016 I updated the Moto 3rd Gen with Marshmellow, and still had the problem. Saw some reviews
indicating Moto 3rd Gen had electrical connector problems with SD card slots so I asked Consumer Cellular
for replacement.

 

MAR 2016 Consumer Cellular replaced the phone with a new one and the SD card worked! I formated
SanDisk 32G Class 10 as internal and used for all photos and some apps.

After a rew weeks of everything working well, phone message SD card not working and should Forget. I did
not select forget several times, and SD card became unrecognizable. Eventually lost all data, and SD card is
totally unusable; Can't even format SD card on phone or PC.

 

JUN 21, 2016 Received new SanDisk 32G Class 10 from Amazon and installed and formated as Internal.
Moved all recent pictures and a few apps.

 

JULY 5 2016 Again, all of a sudden, message SD card not working and should Forget. I selected Forget, lost all
my pictures, but was able to reused the card a portable storage.

 

I'm beginning to believe that the problem is with Android Marshmellow, Consumer Cellular patches, or Moto
3rd Gen device. Also, I just read that the Instagram App can cause problems with SD cards. That app just
updated on my phone in the last 24 hours.

 

I'm planning to test a Moto 3rd Gen that was purchased directly from Amazon to see if I can start to bracket the
likely caueses.

---

Hi MotoMan.

I'm using my Moto G 3rd. Gen since April. IAll the times that the upgrade advice appears I select No, Later, not to do the MM upgrade. With Lollypop the phone works just fine, and I also use a SD Kingston of 16 Gb class 10 without any issue... so I think that the problem is Android 6 and the new SD management it does. 

I have decided not to upgrade at least I see that 6.1 was released and all these issues solved. Now the phone and all its features are operational... I'm new in Android world and I find Lollypop really nice and efficient. I do not want to change that, I'm not desperate for a new OS version until is stable.

Regards.

---

I have decided not to upgrade at least I see that 6.1 was released and all these issues solved. Now the phone and all its features are operational... I'm new in Android world and I find Lollypop really nice and efficient. I do not want to change that, I'm not desperate for a new OS version until is stable.

 

Regards.

---

Unfortunately I upgraded when the upgrade came. I have installed another card as internal and am backing up everything. (I lost some video and photos and some sound recordings lat time.) I have only had one card fail this way. 

Can the upgrade be wound back?

If the current card fails I may do that.

Motorola sais going back to 5.1.1 is not possible, I read it several times over here. I also read that can be done but with issues. 

If you decide to downgrade read here and on other sites to see the whole picture... 

Is incredible what MM is doing to the phone, from an enjoyable device with Lollipop to a nightmare... hope you solve it.

Regards.

Hello Lenovo,

                 You have any solution for it. Or how to get Data back

I have this problem too. NO machine will recognize my SD card. So I bought a new Kingston 32 GB class 10 micro SD card. The phone will recognize it but apps will not save to it, so it is useless.

Many apps wont work without an SD card including my camera which keeps crashing. Sigh... I bought this phone because I thought Goolge made it. NOT so happy about the notification light not working but I could live with that, but now it can't read a micro SD card... are you kidding? 

LENOVO, could you kindly provide us with an update?

SIGH...

Motorola support (Anil) suggested: 

1. Touch  
2. Touch Settings
3. Scroll down and touch Backup & reset
Note: Please unselect the Automatic restore option.
4. Touch Factory Data Reset

Anil: Everything will be deleted in the phone memory not from Sd card.

Anil: Which ever the apps you have moved to Sd card the particular apps will not delted.

Me: What's causing the issue on a lot of phones lately?

Anil: Its might be an issue with 3rd party apps.

Me: Is there some info somewhere to be found on your website.?

Anil: No I cannot please perform the reset steps on your device and cross check with the issue.

So the solution is losing all info & apps stored in the phone's memory in order to be able to retreive the info on the sd-card? Weird!!! 

Has any one tried this?