I have a new P11 Pro gen 2.  Before buying it I confirmed that I supported USBC3.2 and video out via the usb port.
This is essential to my use case, and casting wirelessly is not an option for me.

I just plugged it  into an external monitor using a Lenevo usbc to display port adaptor 
(seen here: https://www.amazon.com/dp/B07C52LQVG?psc=1&ref=ppx_yo2ov_dt_b_product_details)  and get no output whatsoever.  
The tablet reports that it's charging the external device, but that's it.

If I plug the  cable and adaptor from the monitor in to a usbc port on my macbook, it works as expected - so the issue is the tablet's display output.
Any advice?  Am I missing a setting somewhere? 

Hi @cmason ,

Welcome to the Lenovo Community!

And I'm sorry to know that you're unable to get a video output upon connecting the tablet to an external display. Yes, the tablet's USB-C 3.2 Gen 1 port does indeed support DisplayPort™ 1.4 aside from data transfer and Power Delivery 2.0. Although, I have also checked the specifications of the adapter that you have and it appears that it can be only used specifically for projectors and PC. With this, it would be worth to try to use a different cable or adapter instead as there are no compatible Lenovo cables or adapters for the tablet based on the Lenovo SmartFind site.

Thanks,
Adriel_Lenovo

That makes sense - except that the adaptor is successfully driving the external monitor.

If I plug it into a usb-c port on my mac it works. If I plug it into the tablet, it doesn't.

I'll try another adapter, but it seems unlikely to be the issue. I'll need to return the tablet if I can't get this working.

@cmason wrote:

I'll try another adapter, but it seems unlikely to be the issue. I'll need to return the tablet if I can't get this working.

No worries, you may keep us posted here anytime. Although, make sure to inquire with third-party cable or adapter manufacturers if their product is fully compatible when used on the tablet. In addition to that, see to it to know how their store, including their return policy works as well so you won't get stuck with a non-working item if in case it needs to be returned.

Thanks,
Adriel_Lenovo