Supplier with Data Access cannot search for active negotiations for which the supplier isn't invited

Summary:

Supplier with Data Access cannot search for active negotiations for which the supplier isn't invited

Content (required):

We have 2 Procurement BUs : P1 & P2. 

Supplier S1 have sites associated with both the BUs, but, there is a requirement that supplier portal should only show data associated with Procurement BU P1. So, to fulfill this requirement, we created data access restricted to Procurement BU P1 only.

However, if we create a RFQ associated with P1 BU (without inviting any supplier), Supplier S1 cannot search the RFQ. But another supplier (without any data access and site associated with only P1 BU) is able to search and respond to that RFQ.