Looks like you ran out of pickled people ... you might need to attract more dwellers with some addtional installations.
I am so far unable to reproduce the save problem.
Doh! It’s Jiffydos!
I forgot the Miyoo Mini auto saves and loads a save State. Turning the auto load/load state off then turning off jiffydos and resetting, the game loads from the c64 blue screen,(slowly lol). Then the save game works correctly. Switching jiffydos back on and resetting loads the c64 blue screen but save function fails intermittently, but quite offen.
Again this is on the Miyoo Mini Plus my primary device for playing on so I don’t know if jiffydos causes an issue on windows pc, just haven’t had time to test.
ps. The jiffydos roms I am using have the correct Hash value, I checked as to make sure the roms weren’t corrupt.