Solution: After much searching, we discovered it is simply a missing value in the FireFox Config.
- Open Firefox
- type about:config in the address bar & hit enter
- WARNING: modifying these settings could affect the installation/performance of FireFox
- Right Click - New Integer
- Name = network.http.phishy-userpass-length
- Value = 100 (value options are 1-256, start at 100 and reduce to the length of your special URL)
- Close & re-open FireFox & give it a try!