Release: 21.0
Component: Automation Engine
Sub-Component: Unix/Linux agents
This problems was resolved by giving the agent's temp and out directories 777 permissions. From the documentation:
Privileges for the out (UC_EX_PATH_JOBREPORT) and temp (UC_EX_PATH_TEMP) directory (see List of Agent Variables):
Owner: read, write and execute permissions
Group: read, write and execute permissions
World: read, write and execute permissions