Usually I can work with multiple files open within Photoshop. Since the CC 2018 update, an intermittent problem occurs when I have a file open and wish to open a second one in a new tab/window. The second file won't load in the window, the tabs, tools & panels disappear and I'm faced with a blank slate. I can't do anything, even with shortcut keys, so I have to force quit the program. The file size is not an issue and this problem happens with any type of file accepted in Photoshop. Is this a known issue or do I need to do something outside the norm to fix it?