SharePoint On-Prem Table object - Group/Person Data not expanding

Hi All,
I am using SP on-prem as the source for my Dashboard. When reading the Source (tracker as they call it) PBI Desktop shows me 3 types of objects - Lists, Record & Table.
When I expand the List & Record they expand without error but when trying to expand Table - no columns are shown in the expand list and also I face 500 error. 

The particular column I am trying to expand is defines as Person or Group in SP.

Attached Screenshots show the errors and also what happens when I click on the "Table" for a single row (500 Error)

I have tried getting the list of columns in the table - that also throws the same error.