I see the 29500 entered in the Garmin for two of the waypoints. Why is 29500 being used? FL180 and above is controlled airspace. Altitudes are requested/assigned in increments of 1,000 ft for separation. This is what is used by MSFS ATC. If your question is about ATC assigning FL030 vs FL295, MSFS ATC can’t assign FL295 no matter what is in the flight plan. If the aircraft cannot fly at 30,000, then the flight plan should specify lower altitudes especially the Cruising Altitude in the NAVLOG.