I have the same problem as described here.
First I updated Enpass to 6.0 on Android. There it worked without problems and sync with google is working again.
Today I updated Enpass on Linux Unbuntu 18.04. When I want to to init the synchronization, firefox is started on the google pages. I grant the access and than it starts a second Enpass application to process the link, not the one already running.
Rebooting the system does not help.