I have the same issues as budreiser since last update. My aircraft of choice is 747-8i. It flies the flight plan just fine on AP for only part of the route and then I have to take over. The update did FIX my HDG function, which has never worked for me since the original 2020 release (unless I changed to legacy mode, but then I had to manually enter ILS frequencies). While I can appreciate that many users want to enter/load their own more realistic flight plans, I prefer just letting msfs2020 build my route and me only choosing the runways and SID/STAR. Some other things that used to work now don't, but I'll not get into those. It seems that with every update, something that used to work doesn't anymore.
The other aircraft I like to fly is the Captain Sim 777-200 ER. I only mention that because the flight plan still works just fine from takeoff to touchdown when I fly that.