That was my experience with my last flight. I used LNM to create a plan with a SID, STAR, and approach. It looked fine in LNM.
I loaded this in to MSFS, and although all the waypoints were there, it did not treat them as part of an IFR plan. When I entered the sim I wasn’t given the option of requesting an IFR flight. The route was correct as far as RNAV only.