Port concepts are different in these tools. From many years of RFIC inductor simulation experience with both tools: In Momentum, do NOT use port calibration and reference shift. From my experience, Momentum port cal does not work well over silicon, and is not needed. Instead, just place the pins at the inductor and switch OFF port calibration (Feed Type: Direct). Leave the port ground reference as global ground at the bottom of the silicon - that sounds strange for Sonnet users, but works fine in Momentum.
In your Momentum stackup, via8 looks wrong because it does not connect to metal8. It should go down one more layer. At least in previous releases, Momentum thick metal needed to be thinner than the dielectric above them. Not sure if...