Using a laptop. HP Pavilion 15, with Windows 10 Pro 64 bits, version 1809.
Enpass 6 beta from the Windows Store, so it's updated. Latest stable Firefox, ver. 63. The extension I got it from the enpass/enpass-6-beta-downloads/ page
I don't face this issue with other browsers. I have tested this on Chrome, Opera and Edge. Firefox it's the only issue.
I am aware that Firefox needs a bridge connector in order to communicate with the Windows Store version, at least that was the issue with Enpass 5.