You are not allowed to assign a Supplier role to a Service Agent, since the option is disabled.
Reproducing the Issue
- Go to Business Partner Data work center.
- Select Business Partner view.
- Highlight a Business Partner which has the role Service Agent.
- Select Create As button and the Supplier option is disabled.
In principle, there are two types of business partners. They are Business partner organizations (Your business partner is a company) and Business partner persons (Your business partner is an individual).
In this case, Business Partner is a Service Agent who represents an individual and for whom you are trying to create a Supplier role which is a Business partner organizations.
This is not possible as per above definition. Hence, the system works as designed.
Note: Supplier role can be assigned only to Business Partner Organizations.
KBA , LOD-CRM , Cloud for Customer , Product Enhancement