Final Cut Pro X 10.4 — Event / Project damaged

Hello,

I'm having issues with my FCPX library, whilst working between two computers.. I've been working on a project with the library residing on an external disk. On one computer, a Mac Pro, the library works fine, but as soon as I open it on another computer, an iMac 27" in this case; one of the projects (my main editing timeline) is damaged. I'm pulling my hair out. I can't seem to figure out what's going wrong.

Does anyone have experience fixing this issue?