Problem description:
Customer changes item level data in the sales order and other data changes as well.
For example: when storage location is filled in within an item, the order quantity will be changed at the same time (the net weight will be updated with the net weight of another item).
Solution:
In this example after putting watchpoint at XVBAP-NTGEW, VBAP-NTGEW, XVBAP-POSNR, VBAP-POSNR it turned out that there is an inconsistency between VBAP and XVBAP.
XVBAP header line contains a different header item than VBAP (VBAP-POSNR is not the same as XVBAP-POSNR).
Such problem can appear if there is a loop on XVBAP in the user exit, this has the effect that VBAP contains the old POSNR and only the data of XVBAP header line is changed. According to that VBAP-NTGEW is overwritten with the wrong XVBAP-NTGEW and wrong data appears on the screen.
This error usually can be found within userexit MV45FAZZ, in this particular case at USEREXIT_MOVE_FIELD_TO_VBAP.
VBAP and XVBAP have to be in accord with each other, this problem should be fixed.