Support Arc Browser integration with 1Password 8

David from 1Password support offered the following:

I'm sorry to hear that you're experiencing trouble with app integration. I have a few questions to get a better understanding of the situation, in order to provide the best advice moving forward:

Are you seeing the 1Password icon in your Mac menu bar?
Is the "Connect with 1Password in the browser" setting toggled on in your 1Password desktop app's settings? Here's how you can locate this setting:
Open the 1Password desktop app.
Click your account name in the top left of the window.
Select Settings.
Click Browser in the sidebar.
Is the 1Password desktop app allowed to run in the background? Here's how you can check:
Click the 1Password icon in the menu bar and select "Quit".
Right-click your Arc browser in your dock and select "Quit".
Click the Apple icon at the top left of your screen and select "System Settings".
Click General > Login items.
Ensure 1Password is toggled on under "Allow in background".
If you restart your Arc browser and the 1Password desktop app does the issue persist?
Let us know if you have any questions. I look forward to hearing from you and assisting you further!

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I followed the instructions and immediately found that 1Password was not able to connect to the 1Password extension in my (Arc) browser (1Password/Settings/Browser). Changing the system settings on my Mac to allow 1Password to operate in the background (System Settings/General/Allow in Background) and restarting my Mac did the trick.

-- Charlie