I was in the same situation as you with similar symptoms.
I know this won't answer your question but I swapped my '08 7L (non memory) seats for a full set of same model all leather memory R50 seats.
No issues whatsoever, obviously the memory function does not work (nor was it expected) probably due to needing a different module but everything else was simple bolt/plug in and seat adjustment is done manually just as beore.
Very happy with the outcome, these are far more supportive and solved 90% of my issues.
I would love to hear from anyone that has any suggestions on how to obtain full memory functuality.