Hi,
It is difficult to judge what is happening in your case. I suggest that you share a screenshot of the Transformation Rule (so that we can see the source fields and target field). Also I would like to see an extract of the Transformation program where we can see the coding of the respective Transformation Rule.
It has to do with the ALPHA conversion (as set in Characterstic 0RECV_NETW). Within the Transformation this is shown with next to it a checkbox whether the ALPHA conversion should be executed or not. In some cases it cannot be deactivated. Please see also the on-line help for this checkbox.
Best regards,
Sander