Description:
LO 5.x (installed with Fedora package manager/DNF): using my PGP key for digital signatures works as expected.

LO 6 (installed as flatpak in Fedora via Gnome Software): I can select my PGP key in the digital signature window, but clicking on it does not prompt password dialogue box, and the signature space is left empty. No error message.

Steps to Reproduce:
1. Open an .odt file
2. Select File - Digital Signatures - Digital Signatures - (click) Sign Document
3. Double-click on PGP key in the 'Select Certificate' window

Actual Results:  
Nothing happens. The Digital Signatures list remains empty.

Expected Results:
Digital Signatures list should include my PGP key signature, after the system prompts for a password.


Reproducible: Always


User Profile Reset: No



Additional Info:
Note the flatpak installation. I wonder if it's a path issue -- clicking 'Start Certificate Manager' also generates an error message (can't find cert manager), even though I have Seahorse installed and running on the system.


User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/603.2.4 (KHTML, like Gecko) Version/10.1.1 Safari/603.2.4