It works fine for me.
How did you run Electrum? Did you run it without installing it? Or the Linux OS you use is Tails? Because if it's a tails then once you shut down your PC all things you do will be automatically deleted leaving no traces including the notes you save on the Electrum.
I run Electrum from the python .tar.gz archive, which was installed by pip. On Ubuntu.
I should note, that the wallet was closed during a crash. So Electrum did not close normally. So maybe it only saves the notes when you close Electrum normally?
I only have one wallet inside Electrum.
I think you should update your software to version 4.5.3 the latest if it is available for Linux.
There is no point in updating if the changelog does not indicate that there is a bug of this sort that is fixed (and also for security vulnerabilities, but that is a different story and not relevant to this topic).