dop2000 I tried your experiment and I was able to open an earlier version of the file in the latest beta, save it as a new file, close it and re-open it.
I have already tried clearing all browsing/cache cookie data. And as another note, I do remember yesterday that Construct was being finicky when saving. I had both affected project files open and I had to click save several times on each project in order for the save icon to deselect and construct to allow me to close without giving me the "leave without saving changes alert".
I appreciate the help. One of the affected files has virtually no changes from the previous version, but the other has 3 days worth of particularly tedious work that I'd really rather not lose.