After upgrading to Win10 1809 I'm getting more explorer/shell crashes and so I've noticed that the tray icon of 1P disappears.
I have checked that its running until this moment, so the background process doesn't crash as well.
Some other applications also have their problems with shell restarts but there are also others which might have fixed this behavior.
To reproduce you just have to open the Task-Manager and click on the restart button of the Windows-Explorer:
The taskbar disappears then for a short moment and after this the 1P icon disappeared.
1Password Version: 7.3.612
Extension Version: 18.104.22.168
OS Version: Windows 10 1809 17763.194
Sync Type: Dropbox