You have enable the SAPconnect trace and upon checking, the SAPconnect workflow trace list contains no data.
As per the SAP Note 89961 – Workflow Technical Trace not visible, the issue is occurred due to the directory where the trace should be written does not exist. This will be the case when the GLOBAL directory is changed from the standard SAP delivery setting.
Solution
In transaction code FILE, change the assignment of physical paths to logical path of WORKFLOW_GLOBAL_TEMPORARY_FILES to <P=DIR_GLOBAL>/<FILENAME>_<PARAM_1>
