On Monday, October 7, 2019 at 7:00:28 PM UTC-7, wrote:
I thought this problem had been fixed, but it’s back. All my saved routes disappear. There is never an issue with the log files, turnpoint files, or map files. But the routes must get written to someplace that is not stored. And every now and again, they are gone! Is there a fix for this?

I never seen that happen - but as I recall the routes are stored in the Routes.aip file, which you can backup in iTunes.