I've managed to track down what's causing a weird behaviour I've been experiencing the last few days.
Symptom: 1Password Mini (this is what we're calling the browser extension now, right?) won't open (ie. I click the icon, it appears and immediately disappears).
Cause: If the main 1Password window is visible and a Note is opened for editing.
What also happens is that the note stays open for editing but it reverts to the contents it had when it was first opened, ie. changes are lost.
This behaviour doesn't happen if i minimise the main application first - ie. 1Password Mini works, however the changes to the open Note are still lost.
1Password Version: 6.4.377d
Extension Version: 18.104.22.168
OS Version: Windows 10 (1607)
Sync Type: Integrated