This wasn't happening in the previous version of Photoshop. I have Photoshop always open (for days at a time) while working on multiple projects. After a longer periods of time when I don't switch back to Photoshop and it just sits opened in the back, it stops responding when I try to switch back to it. I noticed it's missing an icon in the taskbar and I can't alt+tab to it. When I minimize all other windows and find Photoshop on the bottom it is not posible to click on anything (no tool, no menu item, not even close it). I have to end the Photoshop process in the Task Manager and reopen it. This behavior only started after upgrading to the newest version of PS v20.0.0. Only good thing is I was always able to recover what I was working on thanks to automated backup and recovery in PS.