I'm also having this issue. I don't seem to have another Enpass and rebooting doesn't help. I'm running Mint 19.1 Cinnamon.
When I install enpass, I get a menu item for Enpass. Choosing the menu item doesn't run enpass. I can start enpass from /opt/enpass. Setting up sync takes me to the Google login page and - after I approve - prompts me to open xdg-open. The process never completes, however. Would appreciate any ideas!