Workflow throwing error after approval operation is successful on Active Roles version 7.5

Active Roles approval workflow to add group to the user account is failing to add the group to the user and throwing an error after a approval request has be successfully approved from the approval queue on the user interface. Upon approval a message appears on screen saying the 'The operation is successful' but the group is not added to the user account. 

The event viewer log shows the error details as below

Execution of workflow instance failed.
Workflow name: BESSAdmin Approval

'Details: serviceExecutionActivity1 activity has terminated this workflow instance.
Administration Service encountered an error when making changes to the object 'CN=LIL_Sec_BESSAdmin,OU=Security Groups,OU=Lily,OU=xxx,DC=xxx,DC=xxxx,DC=xxx'.
An internal error occurred. (Exception from HRESULT: 0x8007054F)" 

Any help to resolve this issue is appreciated. Thank you.