Thunderbird delays saving attachment until exiting

Hello!

Whenever I save an attachment, the file does not appear to be saved. It only shows up after I exit Thunderbird.

I've also notice it is working slower, as any new window will appear black for about one second, and only then show its content.

Using 68.8.0 (64-bit) on Debian.

Any ideias, suggestions or hints to what I might look for?

Thanks,