Edge can handle only one password per install

[palant]

Adding a single password in Edge effectively renders browser.storage.local read-only - adding anything will fail with the exception "there is more data available." It took me a while but I eventually recognized https://developer.microsoft.com/en-us/microsoft-edge/platform/issues/8416123/ as the issue here. Passwords are stored under keys that are 94 characters long. Once a single long key is stored this exception will block any modifications, until you remove that key.

[palant]

This was an issue in Edge 38, it is gone in Edge 41. So the solution is to increase required Edge version.