I couldn't find OSS note 6844669 and OSS note 765564 does not seem to be relevant.
This screenshot tells me there is an error in the agent assignment. You should be able to debug function module USMD5_CREQUEST_ROLE_DET (the function module is called from rule AC75700139 from your screenshot above). Place a break-point in the function, then go to transaction SWPR and find the workflow instance with this error. Then, click "Restart Workflow." The debugger should open and you should be able to trace it to see where it fails and why.