ERP Customer UI in MDG - BU GROUPING Error

Experts,

When we explore ERP Customer UI in MDG - in order to leverage the Contact Person UIBB functionality we are getting the following error message:

" Enter a value for attribute Grouping" which is referring to BU Grouping in the data model.

1. How to get rid of this error message?

2. Basic functionality difference between Customer UI vs ERP Customer UI?

appreciate your response.