XBee S1 coordinator not finding end devices

I am trying to set up a network of 1 XBee module as a coordinator and 5 modules as end devices using the XBEE 802.15.4 function set, but my coordinator module is unable to discover the end devices while using XCTU on network working mode. I am using firmware version 10ef (the newest at the moment).

All modules are on channel C using PAN ID BE4. The coordinator modules is DH 0, DL 1, MY 0 and the end devices have DH 0, DL 0, MY 1. All devices are using API mode [1] (a requirement for my project). All other settings are at their defaults.

What can I do to have the coordinator discover the end devices while on network working mode?

The networking mode of XCTU is for the Zigbee and mesh enabled products. It is not for the 802.15.4 product. For that one, you simply need to keep sending the Node Discovery command.