according to the data sheets the APX do not have a dedicated radio in monitor mode. In the helpfile it says that you can start a scan under "Sites". Is there a scheduled scan? I assume scanning also means no client access for the duration of the scan.
Thank you for contacting the Sophos Community.
Currently, the SCAN can be run manually, during this time the connected devices will experience network interruption for 3 to 5 minutes, while the SCAN is running.
The Scheduling of the SCAN is a new Feature request.