Hey steelew, we are sorry for the trouble you are facing in opening Enpass from browser extension. It is a known issue in the latest version of Chromium which is being used by both Google Chrome and Opera and affects both of them while launching custom url scheme from within extension.
Due to this issue, we are removing the custom launching temporarily (only for Chrome and Opera) in the next update as it is crashing the Opera extension too. But to compensate this removal, we are adding another useful feature of "Autorun on system startup", which will start Enpass automatically at every system boot. So you will find Enpass running whenever you need it in extension.
We have also notified the Google Chrome team about this issue and as soon as it is fixed in the Chromium engine, we will re-state this feature.
So I am so sorry to say that until this bug is resolved you have to manually start the Enpass app before using browser extension. Please bear with us for the time being.