I moved to Joplin Portable 1.0.241 / Windows 10 and all was well, but a few reboots I found the app would freeze up when I tried to launch it.
I figured the app was corrupted somehow so downloaded it again and tried to launch it, and I got an error saying the version I was on was the wrong version - database 44 instead of 43.
I was able to get back into my notes by moving to the beta version, which I guess I must use as there seems to be no way back.