Hi,
I always facing this problem every time I got radar vectors by the online ATC (IVAO), mostly when they're vectored me, I simple disengage my NAV Autopilot mode onto HDG. But, only the GTN are updating my Aircraft Track Up, not with the Aircraft PDF/ND so the Heading is stucked. Sorry for my english but I show you a screenshot that you might be understand.
Are these related to the GTN Settings?
https://prnt.sc/sxlxfh