It's hard to tell how I could help you find out what's wrong. If there would be a bug in Enigmail, then your complaint would not help in any way to reproduce the problem of find out what's wrong.
But I believe that the problem needs to be fixed on your side - it's likely not a bug in Enigmail. Please try to follow the advice I gave here about DOS attacks on certain keys:
Zorin 12 = Ubuntu 18.04
Removed, reinstalled, tried again - same result.
Now removed until problem is resolved.
I may be a decade user of this add on, but the current version stops me cold.
Last edit: Reciprocate 2019-07-28
It's hard to tell how I could help you find out what's wrong. If there would be a bug in Enigmail, then your complaint would not help in any way to reproduce the problem of find out what's wrong.
But I believe that the problem needs to be fixed on your side - it's likely not a bug in Enigmail. Please try to follow the advice I gave here about DOS attacks on certain keys:
https://sourceforge.net/p/enigmail/forum/support/thread/d3cf983d0b/