I agree it seems like it's hanging up. The only other thing that could be diferent after install is the ground. But I think I read that you have a ground wire from one of the flange screws. Just keep in mind the flange is isolated by it's gasket and the tank is isolated by pads and so on. Your test may have bypassed those grounding difficulties and therefore would not catch it. Don't know how you did the installed ground vs tests. Did this exact setup ever work installed?

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn