Recently installed the beta 1.18.6 in Firefox 72.0.1 (Ubuntu release 72.0.1+build1-0ubuntu0.19.10.1). Don't expect a linux agent any time soon, but looking forward to Windows integration, so when I'm on my work notebook, I'll be able to use integration there, and fall back to browser only when in Linux, whilst still having my browser profiles synced between machines.
Aaaaanyway, I noticed, possibly since installing the beta, that when I launch firefox, and then click on the 1Password X extension to enter my credentials, if I do it too soon, something closes the 1Password password dialog, and seizes focus back to the main browser window shortly thereafter, resulting in my keystrokes being entered into the location/search bar instead. Bit disconcerting when you start entering password, muscle memory running on autopilot, and then realise you've been firing your master password off into the cloud via DNS request :-/
Besides 1Password X, I'm also running uBlock Origin, NoScript, and Greasemonkey. I do have the non-beta 1Password X installed as well, but it's disabled. I'm using a desktop when this happens, not a notebook, so I'm not brushing a trackpad or the like. I do have Firefox Sync running (but password storage/sync is disabled).
Any ideas? In the interim, I think I'll just pause a bit before I go to enter my password, and keep more of an eye on the focus as I type it