Doesn't recognize mouse clicks until I move the cursor out of the LR window

[Ekir75]

I just installed LR CC 12.1 on my desktop running Windows 10.  I noticed it acting strangely (e.g., not zooming when I clicked on a photo, but then randomly zooming later; masks taking like 10 minutes to pop up, etc.)  I finally discovered the pattern - LR is not recognizing many of my left-mouse clicks until I move the cursor out of the LR window.  For example, in Develop, when I left-click on the mask tab, it comes up as expected.  When I click on the mask type - let's say Radial Mask, it doesn't do anything.  It doesn't freeze and I can click other things as well, but the Radial Mask doesn't apply... UNLESS I click Radial Mask, and then move the cursor down to the task bar or to my second monitor.  As soon as the cursor moves out of the LR space, the left-click that immediatly preceded the move applies.  So, my workflow to apply a mask is click Masks tab, click Radial mask type, move cursor to task bar, click on the photo and set the radial mask (which works fine with the clicks), click on Subtract (works), click on Brush  to subtract, move the cursor (clicking brush won't work until moving the cursor), etc.

I havn't deduced specifically which clicks it's happening with because some of the left-clicks work as expected.  The other one that has been especially annoying is when I click on a photo to enlarge it, it won't enlarge until I move the cursor out of LR.

I've updated my graphic card's driver and uninstalled/reinstalled LR CC.  I've reset LR preferences.  I've reinstalled C++ (which was a suggested fix for a similar issue in another thread), but so far, the problem persists.  Any help would be appreciated as the current work-flow is super inefficient.  

[John R Ellis]

Some more troubleshooting steps:

1. Set Preferences > Performance > Use Graphics Processor to Off.

2. Create a new Windows user account and run LR from there.  That could identify if there are other per-user data files that have gotten corrupted. (A normal uninstall doesn't remove preferences and other such files.)

3. Use the Adobe Creative Cloud Cleaner tool to remove all traces of all Adobe apps and then reinstall:

https://helpx.adobe.com/creative-cloud/kb/cc-cleaner-tool-installation-problems.html

[John R Ellis]

4. Do File > Plug-in Manager, select each plug-in in turn, and click Disable in the Status panel on the right.

[Ekir75]

Thanks!  That first step did the trick.

[John R Ellis]

"That first step [turning off the GPU] did the trick."

Try updating your graphics driver by going directly to the manufacturer's web site:
https://helpx.adobe.com/lightroom-classic/kb/troubleshoot-gpu.html#solution-4

If that doesn't help, please copy/paste here the entire contents of the LR menu command Help > System Info -- that will let us see exactly which versions of hardware and software LR thinks you're running.