2020 3.0 Duramax motor mount issue

[gwm71]

Hello, new member first post.

I have a 2020 LT 1500 with the 3.0 Duramax and I have about 65k miles on it.

 

I've had nearly zero issues since new, but developed a clunk when accelerating after shifting from reverse to drive (not u-joint clunk). 

Anyway, dealer diagnosed both motor mounts failed and replaced under warranty.

My problem started after this, very harsh idle vibration that rattles everything in the truck. Upon returning to have this addressed, I was informed that the truck originally had a solenoid to make the motor mount variable (softer at idle), but was deleted and standard mounts are now used to replace these.

Anyone else ran into this issue?