Lots of buggy issues

I’m working on a project involving a bunch of individual parts. Most of them are simple. But I spent several HOURS trying to create a thread on a shaft (sketch, revolve, subtract) and then using a copy of the threaded shaft object to do the mating internal thread (subtract). There was some issue with getting the subtract on the external thread to work. It eventually did work after some minor manipulations of the sketch. All good! Yay! Everything looked perfect.

I export it to a local file. Close the project. And then I reload it to do some finalization only to see that it’s a mess. No thread on the shaft. No internal thread. A boolean error on the shaft thread creation (that wasn’t there before). Even the object with the shaft that had been moved to do the thread creation is not in the proper position. It’s like a bunch of steps in the history were not retained. Even the ‘thread revolve object’ doesn’t look like what I ended up with in the successful process.

Am I screwed (no pun intended) and need to do this over again or is there any means to recover whatever got lost in the process? I will provide the project if you want to analyze it.