Apple Watch unable to unlock 1Password after updating to Tahoe 26.4 (with Solution)

I would like to share my experience about unlocking 1Password on Mac mini with Apple Watch.

I have M1 MacBook Pro and M4 Mac mini both 1Password installed. As the keyboard I use with the Mac mini is not Touch ID capable, I use double tap on Apple Watch to unlock the 1Password.

However, after I updated OS to Tahoe 26.4, double tap request stopped appearing on my Apple Watch when I open 1Password on Mac mini. Other than that, double tap on Apple Watch still works just fine to give permission when macOS system prompt requests, such as when turning on "Log out automatically after inactivity”. in Advanced window of Privacy & Security setting. It means the trouble happened only with 1Password.app. Curiously, no such trouble happened at all on MacBook Pro with the same Tahoe 26.4.

I searched for related information on the web including this community, and tried the followings to solve the trouble, with no success.

• recheck the settings of “Touch ID & Password” of Mac mini and “Security” of 1Password.app 
• restart 1Password.app
• reboot Mac mini and Apple Watch
• safe boot Mac mini
• toggle on/off wi-fi and bluetooth on Mac mini and Apple Watch
• toggle on/off “using Apple Watch to unlock” setting in 1Password.app
• uninstall 1Password.app and the related data from Mac mini according to the instruction on Agilebits support page and reinstall the app

And finally I have solved the trouble today. 

Rather than simply toggling on/off wi-fi function of Mac mini, I switched its wi-fi networks from my home wi-fi router to the shared wi-fi network of my iPhone paired with my Apple Watch、and suddenly “unlocking 1Password.app by Apple Watch” function has come back. After then, even if I switch Mac mini’s wi-fi connection back to my home router, it keeps working.

So I guess 1Password.app on Mac mini, for some reason, had lost contact with Apple Watch　even when its macOS still did, and that was the cause of the trouble.

Of course this may not always be the case, but I would like to share my experience here for someone who may encounter the same trouble in the future.

By the way, I reported the trouble to Agilebits support for their help using the contact form a week ago, and got no reply so far other than support ticket ID.