Whenever I read these posts I get the impression that contributors are talking about free ice floating around in the fuel.
I see this ice, whether it be from water in the fuel or the result of condensation being a sudden release, either due to temperature, flexing of the wing or vibration, of ice which has frozen and adhered to internal wing surfaces during the flight.
i.e. all the scavenge systems, fuel mixers and heaters could never touch this ice as it was attached firmly to a surface and released itself in quantity at roughly the same time, thereby clogging momentarily, the filters to the pumps.