I suspect that somewhere along the line you moved the source media that went into the project.prel after the project prel (project file) was saved closed. Let us see.
But, I need to go through your details to see where that might have happened. I want to make sure we are distinguishing between import source media, source media on the Quick view Filmstrip, source media on Expert view Timeline, and the export of the source media to a file.
1. You set up a project with video and photo content in the Quick view. And, uploaded that to YouTube. Am I correct that the uploaded to YouTube was from Quick view Filmstrip via Publish+Share/Online/YouTube?
2. What did you save when you wrote
I then opened the completed video file and saved a copy.
Was that a copy of the project.prel (project file) that you saved via File Menu/Save A Copy or something else?
3. Then you wrote
I then opened the copy and clicked the "Expert" button. After the screen had changed to go from "quick" to "expert" I noticed that one of the pics in the video was cut and replaced with a red and black screen that says "media off-line" in several languages.
Assuming that is the copy of the project.prel file and given that you switched to the Quick To Expert view and noticed a missing photo (.tif) when viewing in Expert view, what next?
a. When you first opened the project.prel copy, apparently it opened in Quick. Did you see the photo at this point?
b. When you went to Expert view and found the photo missing, did you go back to Quick? If so, was the photo still there?
4. Do you have any drive letter changes going on in all this? Where is the source media for this project saved?
Please review. Your reply will help us to help you resolve this matter.
It is not uncommon for the Quick view not to offer features or present as does the Expert view. But I have rarely if ever run into instances of the reverse.
So, please check the save location of the "missing" photo in Expert as to what is going on there. Premiere Elements project has only copies of the source media and these copies link back to the originals at their hard drive save location.
Yes. Thank you for the reply. The first thing you said was it. The source media got moved. I fixed that and it worked fine. Thanks.
Great news that the issue is resolved.
Thanks for the follow up information. Much appreciated.