Seahorse unable to import pkcs12 certificates in Ubuntu 18.04 LTS
seahorse 3.20.0-5 / gnome-keyring 3.28.0.2-1ubuntu1.18.04.1 / Ubuntu 18.04 LTS / GNOME 3.28.1
When trying to import a certificate into seahorse/gnome-keyring on Ubuntu 18.04, seahorse GUI application shows the 'import' button greyed out, while mouse hovering the "import" button shows the message "Cannot import because there are no compatible importers".
** This problem doesn't occur on Ubuntu 16.04 LTS (Seahorse 3.18.0), as I've just tested on my wife's laptop, but happens in my Laptop with Ubuntu 18.04 LTS (Seahorse 3.20.0-5). **
Because that problem, it's not possible to digitally sign documents with LibreOffice.
-- This bug was first reported on 2018-05-17 in Launchpad's Ubuntu Seahorse Bugs: https://bugs.launchpad.net/ubuntu/+source/seahorse/+bug/1771880?comments=all, and currently affect at least 43 people, but for some reason was marked as "wishlist", supposedly because it is an "upstream" bug, despite the fact that the problem didn't happen on a previous Ubuntu version (16.04).