US XT1064 running stock, locked bootloader, unrooted, lollipop 5.02

I have selected a ringtone in Settings/Sound & notification/Phone ringtone.  It is a custom ringtone stored on the SD card.  The ringtone does not play when a call is received from someone in my contacts list.  A different ringtone plays.  When I select a contact, choose edit, choose settings, then Set ringtone, "Default ringtone" is selected.  The "Default ringtone" that plays is not a ringtone listed anywhere in the Settings/Sound & notification/Phone ringtone list.  I don't know where this "default ringtone" is coming from.  If a contact has a custom ringtone from the set ringtone option, it plays the custom ringtone.  It's just any contact with "Default ringtone" won't play my chosen one.  How do I set the "Default ringtone"?

This worked correctly on KK 4.4.4.

Maybe try moving your ringtone to internal storage? If the SD card is not accessible for some reason, when the call comes in, then the phone will use the default. 

Your ringtones will show up in the list if they are in the ringtones folder - On my X I have a ringtones folder under sdcard (the internal) called ringtones - and that is where Android looks for ringtones by default. If you copy something here, it is available to pick as a default. 

Solved the issue by moving all ringtones and notifications to internal storage.  This definately changed after lollipop.  I have had custom ringtones and notifications on my external sdcards since gingerbread.  All were in their respective folders and all were listed and selectable in lollipop drop downs.  It's just they would not play from sdcard.  Phone would always play default, which did not match my selection.  Definately worked on the G using kitkat, not now.  Even tried factory reset, mount/unmount sdcard, no change.  I got tired of missing calls and messsges.  Just have to use internal storage now.