I'm encountering this same issue (no queries displayed in the SAP Queries dialog box when pressing the Refresh button) and am seeing the same 'Selection screen is too large' error in the log file; e.g.,
/QTQVC/QUERY_CALL_CATALOG failed after 00:30:20 Key = Error in generated report (Selection screen is too large)
According to the same log file, I'm using QvSAPQueryConnector.dll 5.7 SR1, 10958.
BTW. it takes about 30 minutes for the Refresh process to complete ... and to result in showing no queries in the dialog box.
How can this issue be resolved?