Xtend modems in User Defined tx\rx mode ignoring dipswitch settings

I am trying to use Xtend-PKG ( and OEM) RF modems in the User Defined mode - setting the MT (MultiTranmit) to 0 so RR (retries) will not be ignored. Using the XCTU program I wrote the new values in to the registers but when I read them back some of the units will have MT reverted from 0 back to 3 again. On the PKG version the dipswitches are set to 100011 and the firmware version is 2067. I’ve tried restoring the factory defaults using XCTU and this doesn’t help. Are there other settings that need to be changed to allow the User Defined mode to work?
Also, how is this handled in OEM - does it assume User Defined mode - if not how do I put it in that mode?

The function of determining user defined mode is done solely on the use of the dip switches and not the OEM module. If your radios are not doing that, then they may be old enough that you need to install a jumper just behind the switches.

Thanks for the response. Are there any markings that would indicate whether or not the units were “old enough” that the jumper is needed.
BTW - all units were purchased within the last year (I know that isn’t any kind of guarantee of the revision of the HW but just to be clear).
And do I understand correctly that if I put an XTend-PKG into user defined mode there is no way to then communicate with a XTend-OEM module (as there are no dipswitches on it)? We were told the two devices are compatible.

No you did not understand that. The Standard alone RF modem uses the exact same OEM module and firmware you are using now. So they are completely capable of communicating with each other.

Do they all say Digi on the outside of the box or do any of them say MaxStream on them?

All say Digi on the outside.
Good to know they are compatible. Do you know of any documentation that explains how to design the circuitry needed for the external dipswitches to the OEM modules to achieve the user defined mode?