Cubase 11 Linked channels losing 'link' with Mackie MCU?

Would someone with an MCU Pro mind checking this for me?

I create 2 audio tracks and link them. (volume) Then on the MCU, play with the fader of one track for a while, some extreme motions if you want. After a bit of movement, the faders are no longer matched.

Am I doing something wrong? Any ideas?