Problem

--If you are trying to add a new user attribute to a BDOC (tracked object) the elements from the assigned map will start from 1 and not from 0 and probably you will received an error

-- See the attached screenshot (in the before_workaround.png the "AgentlPAddr (S - String)" is set at the position 1)

Resolution

**You need to create manually the TO (tracked object) including user attributes outside Mapping Services, then import the TO into Mapping Services (in the after_workaround.png the "AgentlPAddr (S - String)" is set at the position 0)