As you're facing trouble with Photoshop & the tools stop working whenever to come back to the application, could you please try resetting the preferences of Photoshop & let us know if it helps?
To restore preferences quickly using a keyboard shortcut: Press and hold Alt+Control+Shift (Windows) or Option+Command+Shift (Mac OS) as you start Photoshop. You are prompted to delete the current settings. The new preferences files are created the next time you start Photoshop.
Also, please let us know which version of Photoshop are you using and which operating system are you working on?
I did this, does not solve the bug. All apps are current. How can you guys have such a problem?