Cross Dissolve not copying and pasting properly from one project to another

I created a multicam project with video and audio and plenty of cross dissolves in the audio and many cross dissolves in the video file as well. It was a 50 minute 4K seminar video, and when I went to export it, Final Cut Pro crashed. I attempted a fix (that has worked before) by copying and pasting the entire multicam clip, with it's added text boxes, cross dissolves, etc, into a brand new project. When I went to export, it still crashed. After many attempts at exporting, I finally realized that the Render Files were over 1 Terabyte in size for this 50 Gig movie. I deleted all the possible Render Files and one back a Terabyte of space. When I went back it to export the movie, the newly created movie with the copied and pasted clip exported successfully without crashing. Only thing was, at random locations throughout the movie, the cross dissolves had been automatically and randomly lengthened, in some case to 30 seconds long, so that I was hearing unwanted audio under the main audio. So I went back in and tried to export the original project that was unaffected, but Final Cut Pro crashed again, leading me to believe there is some other kind of bug in the original project, and not just the issue with my external 3 terabyte hard-drive being too full to successfully output the movie, as I had originally thought when I deleted the Render Files. So now I am going through the newly copied and pasted multicam clip in the new project, and fixing each of the dozens of cross dissolves. Has anyone experienced this kind of thing? Here's a screen shot of just a few of the elongated audio cross dissolves in the newly created project. Note I am using a brand new MacBook Pro Sequoia 15.3.2 with a terabyte of RAM, and the Final Cut Pro Library I'm working from is on is a 4 terabyte Lacie Rugged external drive plugged in with USB-C.