I have added 5th customer field to MARA table which is used in MM17 transaction .
When the user is doing other customer field change (like gross weight,order date) (using MM17 , by default the newly added 5th field getting changed with value "/" visible in change document .
Please see the attached document for details.
you have not attached anything-
Mass Maintenance of append fields is a missing function and could only be achieved following the guidance in OSS note 576160 - MM17: BAdI implementation for append fields
So your append fields are probably affected by some wrong coding.