LO6 on Ubuntu - no OpenPGP key recognition

I am using LO Version: on Ubuntu 18.04 MATE. I have and use numbers GPG keys, both on the file level and via Thunderbird. When I use LO, when I go to Options → LibreOffice → User Data, on the bottom under the heading Cryptography, I only get “No key” as an option for both OpenPGP encryption and signing key.

Additionally, the key sets are recognized by seahorse, gpa and gpg (via terminal).

Is there a setting somewhere that tells LO where to look, although the keys are stored in the default used .gnupg folder?