3288650 - OwnerId field is showing 'null' value for attachment entity when added in Custom MDF

When querying Attachment entity, the ownerId field is empty for attachments from custom MDF objects. This doesn't occur in attachments from standard objects, like National ID or Payment Information.

When looking at the API logs, you can see that the empty ownerId returns as following:
"ownerId": "noOwner"

The expectation would be the way the ownerId returns for standard objects as below:
"ownerId": "xxxxxx"

• SuccessFactors OData API
• SuccessFactors Employee Central HCM suite

noOwner, Successfactors, Attachment Entity, Odata API, SFSF, MSF, Custom MDF Object, Employee Central Data Subject Field , KBA , LOD-SF-INT-MDF , Metadata Framework API (MDF) , Problem