Yea, Apple seems to be going off the rails lately with software quality. I'm still on Sierra on my Mac, but Garageband and iMovie both have serious problems lately - updates schmupdates!!!, and I've not monkeyed with anything since a fresh install of Sierra last May.
Thankfully I have full clone backups via 'Carbon Copy Cloner', and because I simply lack the time and patience to troubleshoot these issues -- Instead I'm going to wipe the drive, and do a fresh install of everything and then copy my home folder over from the backups, which sounds like a lot, but is much less effort than going down the rabbit hole and trying to fix things.
Moral of the story is that we should ALWAYS have a backup, somewhere, and for good measure a second backup just in case the first backup gets corrupted or becomes inaccessible....
Linda, I'm very glad you were able to get back up and running and did not lose any files. It can be really heartbreaking when you lose something that you created and spent hours working on, an then to find 'poof' it's just gone...