I looked to see if anyone else was experiencing this issue, but I couldn't find anything. Sorry if this has already been reported.
I updated this morning to the latest version of the Alpha (released Nov 17, I think) and got some weird behavior. Whenever I open the app, I am unable to select the Master Password field to enter it. Tabbing on the keyboard doesn't work, clicking on the field doesn't work. I recorded a short screencast to demonstrate the behavior in case you see anything that can tip you off as to what's going on. (I was attempting to type between the clicks in the video)
I'm running the latest Windows 10 inside of a VMWare Fusion VM, with OS X as the host. I'm using touchpads, and couldn't get it to work with my Macbook's touchpad or with the Magic Touchpad. I unfortunately don't have a mouse handy to see if it's just a case of pointer events not being registered correctly.
Let me know if you need any other info.
-- Bryan Helms
1Password Version: Windows Modern Alpha (Nov 17 update)
Extension Version: Not Provided
OS Version: Windows 10 (1511, Build 10586.3)
Sync Type: Dropbox