XT09: Having problem saving KY parameter...

I have two radios. The first radio is a XT09-SI module with Firmware 206E; the second radio is a XTend-PKG with Firmware 206E. I have both radios communicating between each other just fine. I’d like to add AES Encryption (KY Parameter) to encrypt the traffic.

The XT09-SI module accepts the 64 digit HEX key just fine.
The XTend-PKG fails to write the 64 digit HEX key.

I have rolling back both radios to firmware 2067 and rolling forward both radios to firmware 206E with the same result.

I have upgraded XCTU to the latest version with the same result.

I have attempted several different keys with the same result.

Aside from DT and MY both radios have the same parameters.

Anyone know what I am doing wrong?

Are you using the Modem configuration tab to write the parameter with? That is, read the one, set the Key and click on write. Then swap radio and click on write again.