With exec.queue.enable=true and exec.queue.timeout_millis=300000 (ms), the data for timed out queries due to exceeding the exec.queue.timeout_millis limit in the WebUI shows as:
The "05 min 0.030 sec" value should be for the "Queued" key instead of the "Execution" key.
Also, the error in the log file for the query is shown as:
"RESOURCE ERROR: Query timed out of the large queue after 300 ms."
It should say "... 300 seconds"