Changes lost if not saved

[Mick Sulley]

Running Eric 21.5 on Linux Mint 20.1

If I make changes to a file and then close eric I get a prompt ask 
whether to save changes or not.  That is good, however, if I make 
changes and then close Linux there is no prompt, Linux closes and the 
changes are lost.  When I restart and open eric again it says that a 
session crashed, do you want to recover, but it recovers the last saved 
version, so the changes have been lost.

Is this a bug?

Thanks

Mick