<Alt-F11>? Hey, that's cool; I didn't know about that shortcut. (I always use <Alt-L>,V.) Well, I don't know what to tell you about locked projects. If you're willing to upload the workbook, I can look at it myself; and if it does the same thing for me, I'll play around with it, see whether I can figure out why.
If your workbook contains sensitive material and you should not upload it, maybe this will help: I just googled "excel project locked" and it came up with a number of pertinent-looking discussions, including
this one which is out of date but clearly on-topic; maybe one of those will clear things up for you.