iMovie won't share to social media format, problem with external drive??

Working with iMovie 10.4.1 on IOS 14.5. My project was created on a Mac mini (M1) then moved to external hard drive (Sandisk SSID 1TB). When connected to my MacBook Air (M2), I can open project and work on it. I cannot move the project to a different library (greyed out) and I cannot share for social platforms. Sharing to a file works. I get no error messages or warnings. The operation doesn’t complete. When I try connecting the external drive to my Mini and opening the library in iMovie on my Mini, the project doesn’t appear at all. I’ve done First Aid on the external drive and it’s OK. I’m trying to save my project and I don’t want to have this problem and potentially lose other projects. Not sure if there is something wrong with the external drive or I’m doing something wrong in iMovie.

Thanks.