Current file window hides if I exit photoshop and return

This is driving me crazy

Whenever I go out of photoshop to check email or do anything else and click back in, the window I was working on appears to be gone. Any open file windows behind it are still there. If I select the Window menu, it shows my current file checked as the active window, but it won't reappear unless I select it from the list anyway.

In my work I do a lot of blended Photoshop/Illustrator files that requires me to click back and forth and refine smart objects in illustrator. Now, after the last update, I have to select the file from the window menu  in photoshop to see and access it.

I have been working in Adobe since 87. I have never seen this behavior before. Is this happening to anyone else