Error in Manage Service Provider Relationships

Summary:

In Manage Service Provider Relationships task, under Service Provider BU (Procurement), I am trying to add multiple BUs. But after adding 11 BUs, I am getting below error when i add 12th BU. The same error occurs when I try to add all BUs at once as well.

Error:

Unable to retrieve content. Additional information for "Remote Region error #19":

An error occurred while invoking task Manage Service Provider Relationships. Review the FunctionalSetupServer logs for more details on this error. Contact your help desk..

Can someone help me out with this error please?

Content (required):

I am trying to define a single BU as Service Provider to multiple BUs as per client business process. Hence trying to establish one to many relationships for all the BUs.