I also cannot get the 1Password Mini to operate in Edge. I have verified that the '2bua8c4s2c.com.agilebits.1password.json' file is in the NativeMessagingHosts folder for /Chrome and for /Chrome Canary and for /Microsoft Edge.
All I get when clicking on the 1P Mini icon in the menubar is the message 1Password extension (desktop app required). Quitting and restarting 1Password, 1Password Mini, MS Edge, and the Mac have not solved the problem. Any other suggestions ?
to add to the above comment - - I am using 1Password 6.8.9 with Edge 87.0.664.47. I also use the Chrome browser (v. 87.0.4280.6) and 1Password Mini works fine with Chrome.