Certain buttons no longer assignable

Earlier I was able to assign the Next and Previous midi buttons to my Mainstage.

I was surprised to see that the Controller Map has disabled the Next and Previous button assign.

Why?

I rolled back my MCC to the previous version and just keep saying no to it asking to upgrade (downgrade in my opinion) to the newer version.

I use MCC with my minikey 3 and it offers better functionality with 1.17.