AG Command not working as expected

Hi
I am having some trouble setting up my DigiMesh network. I am using the XBee3 XR 868 Modules with the latest firmware (A002). I have a single receiver configured and have multiple endpoints that I run in transparent mode. The intention is that all of the endpoints only send to the single receiver. I have set up the network so that the DH/DL parameters in the endpoints are setup to match the MAC address (Serial No) of the receiver, and this works exactly how I would like, with only the receiver receiving the data packets. This however requires me to hard code the know MAC address.

But I need to be able to reconfigure the network in real time with only a direct connection to the receiver. So I am trying to use the AG command as in the example below.

Example

For this test I have set the DH/DL of the endpoints to 0x0/0xFFFF
I then send an ATAG command to the receiver via XCTU command console, as per the example above. I sent this command with both FFFF and FFFE parameter values, and in the case of FFFF expected to see the DH and DL values of the endpoints change to the MAC address of the receiver, but this did not happen. Can anyone give any advice on why I cannot get the endpoints to update?
Many thanks in advance

May I suggest submitting a Case for this issue by going to https://my.digi.com and logging in.