Problem loading older files (Oct 2018) into Layout

I’m shifting over to a new Mac Pro (OS 11.1) into which I have loaded Sketchup 2021and finding that I cannot get certain older files to open from a hard drive. I have run disk utility on the hard drive and I guess it’s okay. Some older files open and some do not. I guess the question is, has anyone else experienced similar problems and is there recourse. Thanks