I talked to Mike for a while, and I believe there might be some issues of PasswordMaker with auto-populating of custom password fields on his system. He uses Linux/firefox, and the behaviour was different from my Windows/firefox, on the same website.
Problem: although everything seems to be set up as it should, PasswordMaker uses the generated password instead of populating the password field with the value stored in the auto-populate tab. Are there any known issues with Linux or other/older versions of firefox?
I will try to set up a linux system to maybe recreate the problem.