I upgraded my Mac OS to version 11 a few weeks ago. I was almost done editing a travel movie that contained lots of .mov files from iPhones and cameras. When I opened the project it asked the location of the .mov files. I was suprised because I had not moved them, but I selected the location and the selector showed the first frame of the video I had selected. Then the program immediately asked me for the location of the file I had just input.
The still files that are part of the video are found with no problem. It is only the .mov files that are not recognized. I tried deleting them and re-adding them - and even tried to start a new project. No .mov files are recognized. These same files are recognized in other video editing programs and players, so the files are not corrupt. They were read just fine until I did the Mac OS upgrade.
At the time of the error, I contacted support and they said a software patch was coming. That was weeks ago, and I'm starting to think I have been abandoned. I recently upgraded Premeire a few months ago when I bought a new computer. So I'm feeling like the new software was a bad investment.
Premiere Elements doesn't randomly lose file connections. Did you start your project on your older version of Premiere Elements and then open it in your upgraded version? It sounds like you were working on the project, then upgraded your computer, then bought a new version of Premiere Elements and then, finally, renewed your work on the project.