In 1Password 7.7 running on Mojave 10.14.6, if I edit a login and then cancel or save in 1Password Mini, the red/yellow/green buttons disappear. I have to fiddle with the window in some way to get them to come back before I can close the window. I have reproduced this on two computers.
Here is a movie: https://we.tl/t-KUx9jVICc9
1Password Version: 7.7
Extension Version: Not Provided
OS Version: MacOS 10.14.6
Sync Type: Not Provided