Possible , not impossible
One centre tank water scavenge jet pump suffers poor flow due to 6 mm disc
Frozen water accumulates to be discharged at late stage of centre tank scavenge.
Hard ice crystals abrade fuel pump surfaces
Can frothing occur also?
One of the crossfeed valves neither fully open nor closed after crash,(and according to Captain MM would not have been selected open in any case(?))
The enquirys lack of comment indicates it to be serviceable,
But if it had in fact for some reason remained half open throughout the flight it would supply the missing common factor complete with 7 second interval