Jurgen, I agree with you...
Regarding the EKPO-WEBRE it was stupid from my not to consider that we do not have an invoice if the purchase order line is free of charge...
we did updated with an enhancement in MM06EF0B_BUCHEN
The other flag EREKZ is updated with a batch input that runs at night
We corrected the enhancement so we check both WEPOS+REPOS
still I have about 100 positions that have wrong data ( does it matter ? SAP is complex I really do not know if those flag are involved in some other program/transaction but I bet thet are...)
plus I can not perform my return to vendor
Maybe we should also modify the batch input in order to skip the free of charge positions and not update the EREKZ
In the meantime you think it is "safe" to update the field via SE16 ?