MCU XT Pro - Listen Mode not working

Hello
Having recently added a Mackie XT Pro to my MCU Pro I have run into the following issue:

Per the Steinberg documentation (Mackie MCU Pro page 13) pressing Shift+Project on the MCU Pro changes the function of the solo buttons so that they trigger Listen Mode for the relevant channels. This works fine for the MCU Pro main unit but is not reflected in the MCU XT Extender Pro where the solo buttons continue to activate normal solo mode.

I make extensive use of the MCU units so it’s a shame that this function does not work consistently in my new setup.

Many thanks for any advice or potential solution.