VERIFIED SOLUTION i
'com.pb.viewpoint.rest.client.spring.CustomResponseErrorHandler] unable to process JSON' error message is being observed in core ('admin-services') logs of EngageOne Server while submitting the document and selecting the role mapping icon.
This could be due to know defect before EngageOne version 4.4.7.
ResolutionUPDATED: September 13, 2018
It has been fixed in EngageOne Server Version 4.4.7. Hence, upgrading to these or later releases should resolve it.