Photoshop 2020 stops functioning properly when running in background

[MOWADesign]

I updated to the latest version of Photoshop because of funky behavior in the last one, but it persists.

Photoshop is always up and running in the background, as I'm using it throughout the day. The problem is, if I open Lightrom Classic, my other mainstay, Photoshop goes wonky, manifesting in various ways:

1. All the files I have open appear black. I can see all the image data in the layers panel thumbnails, however the image itself is black. If I copy it and paste it into a new PS file, nothing pastes. I can paste it successfully into other apps, including CC2019 and CS6.
2. The image appears fine in the window, but all the layers, including the background image containing the full image, are blank. I can copy and paste the image into a new PS window, but the layer still appears blank.
3. If I apply a filter to a layer, the layer thumbnail in the layers panel goes blank (not black—BLANK).
4. The marquee, lasso and text tools cease to function. 

The one constant is that Lightroom Classic and Photoshop 2020 do not play well together. The only way to restore Photoshop's proper functioning is to quit PS and reboot, which is hugely disruptive to my workflow.

I'm on a MacBook Pro 2019 running Catalina 10.15.5.

Please get your photo suite working properly. I make my living with these tools, and considering the pricing and limited product bundling options, I'd think you could make your software arsenal more stable and reliable. Even Lightroom I had to roll back because it became impossible to load a slideshow without it choking.