Mozilla is not allowing the page to redirect to Bill Pay due to the Accessibility settings.
This can be fixed by clicking on the menu (3 bars) on the top right, selecting Options/Preferences ->on the left side, select Advanced-> Under Accessibility, uncheck ‘Warn me when web sites try to redirect or reload the page’
If you do not want to uncheck the field, the following option will also work, but will have to be done every time you access Bill Pay.
Click on Bill Pay tab. Right Click on the white screen, select ‘This Frame’->select reload frame. A banner will appear asking you to allow the page to redirect. Click ‘Allow”.