There weren't any major Windows updates recently, but Windows is constantly installing updates in the background, so what do I know...
I'm running Enpass version 5.6.19 (5548) and Windows 10 Home, Version 1803, build 17134.165.
I don't have any additional antivirus software installed.
I re-installed the extension. It worked once. After that it worked a second time, but it did not recognize which password to chose, so it showed me a list of the passwords I used recently. And after that it stopped working alltogether, so nothing happens when I click on it.Then I re-installed the Enpass Client as well. After that it worked once, before it stopped working again.