Today I logged into the Agilebits forum page. Straight after logging in I got a dialogue box from 1Password offering to save my password. Of course I said, "save it". I logged out so that I could test. 1Password failed and was unable to login.
The problem seems to have been caused by the floating dialogue that the AgileBits forum generates when you wish to login. Here's the URL that 1Password automatically stored with my login credentials:
This is what I had to manually set the URL to in order to get a successful automated login using 1Password:
It would create a better impression if the forum integrated better with the 1Password software.