Hello Thomas,
unfortunately I am very sure that my post will not help you anyway - but your problem seems to be very similar to mine. As you just described before the MCP2 Displays are updated with informations coming from the T7 but I can also not do some inputs from the MCP to the T7...
The only difference between your problem and my problem is that in my case it didn't work before with the T7...The PMDG 737 NGX works excellent with Linda and the MCP2 in my case, this is also the reason why I dindn't try any reinstall up to now...
It would be great if you could give me any information if you could solve the problem in between or in the future - I will also do the same...
Greeting Thomas