@Reef-a-Holic, EAPs cannot be placed off the map canvas completely.

Check whether it might be on a different map. You can define more than one map per site. Also set minimun zoom factor (see red arrow).

@Reef-a-Holic, I noticed during tests that devices casually can disappear when one is connected to the controller through the TP-Link cloud and the connection times out. In this case, a reload of the web page causes device icons to re-appear on the map. Of course, forgetting the EAP and re-adopting it helps, too.