Position-based Substitution work item not shown

Hi,

I need to use position-based substitution in SBWP.

This is because person A holds several positions.

However, work items were not found in person B's SBWP inbox.

Substitution was active and adopt substitution was ensured. Still there is no work item found.

I check the table in HRVPADD2 and HRP1001. There are records for the substitution.

Is there any missing authorisation or configuration i need to set for the workflow?

Please advise, thanks

Regards,

Gary