IDE 2.x randomly fails to find all OTA devices

Hi, I am using 15 ESP32 devices, cooperating using ESPNow. Program upload is done by OTA. However, the list of selectable devices in the IDE (using the Tools|Ports menu) is regularly not listing all devices. OTA devices mysteriously disappear and show up again without any particular clue. I'm using IDE 2.3.2.

Any idea what's going on and how to fix?

Regards,

Peter