Photoshop Not Recognizing AMD Graphics Card When Sidecar Is Enabled (macOS)

I have this same issue did you ever find a fix? I started getting lagging graphics, screen glitches, and eventually full computer crashes and I think I've narrowed it down to sidecar being the issue.

I got a new iPad and linked it through sidecar once and I think that's when the issues began. I have since disconnected it, but the crashes still continue. I have this problem while using Lightroom though, so it may be a different cause. I'm hoping there's a fix because I can't seem to find a way to signal to the application that there's no second display being rendered. 

I just ordered a PC Tower.  I heard that there were some issues with the AMD cards.  So.... I switched to nvidia. 

But I heard about issues in relation to Premiere Pro.  So glad, that I switched the order to nvidia.

Hopefully you can find a solution.

the sad part is that it would be simple for Apple to route sidecar past the Gpu in the same way Microsoft does with dual Gpu laptop chips and just fake the Vram [again like Microsoft]... they just can't be assed

Photoshop has no problem with multiple monitors (I use three here) provided they are plugged into a single GPU. Running multiple GPUs with conflicting drivers is known to cause issues and is not recommended. See section 7 & 8 here:
https://helpx.adobe.com/uk/photoshop/kb/troubleshoot-gpu-graphics-card.html

Dave

I should also probably point out that I'm not using the iPad area as the window area for Photoshop- I keep it on the main Macbook Pro screen. I like using the iPad for putting Mail and Slack in. But just having Sidecar on confuses Photoshop - maybe because Photoshop is getting false graphics card info from the OS?

Sidecar is really a Mac OS feature that fakes a second monitor. I've never had good results with using it with Photoshop. A future release may address this, but for now I would consider it unsupported in Photoshop.

Almost the same here. Having iPad Pro in vicinity of my own Macbook Pro 16, even with Sidecar mode off, when starting Photoshop screen begins to blink, then PS reports about GPU not being available, and in Preferences/Performance there are no options to change Graphic Processor Settings. Also there is annoying bug/lag when using scrubby zoom when panning/zooming canvas using space bar and mouse. Thank god that build-up bug was removed in recent release....