Thanks Joy! Between the time you authenticate to the 1Password engine (the TouchID prompt at around 0:05 in your second video) and when we see the "Search 1Password" and list of creds to select from, I'm wondering if you had to perform any further input (keyboard, mouse, trackpad) - or if it just happened automatically as a result of your successful auth to 1P8?
For me, the challenge was (and unpredictably, but still sometimes is) that once I've auth'd to 1P8, nothing appears on screen until I hit the [Cmd]-\ keyboard shortcut again.
I've been on the Nightly channel for a couple of months (currently running 8.10.5 with 2.7.0 extension), and I am pretty sure I've still seen this lack of response after the auth succeeds, but I did just try this now - locked the extension and desktop apps, opened the reddit.com login prompt, hit [Cmd]-\ shortcut, auth'd with TouchID, and saw the "Search 1Password" UI overlay within a couple of seconds - so it isn't as reproducible as when I reported this back in January. Maybe there's some extra timeout that happens when the extension/desktop app have been locked for a while?
Either way, I felt bad about leaving this unanswered, and evidence is encouraging though I'm not convinced I haven't seen this get in my way recently - but maybe I'm just imagining ghosts in the machine.
