Topic: playing 4k home videos via usb issue

hi all
have hit an issue with trying to play 4k videos via the usb stick 3 plugged into the xbox series x. it is formatted ntfs and video is saved as mp4 and h.264 as advised by microsoft but constant buffering starts 5 secs in and does not resolve........even tried loading videos into xbox but no, still buffers constantly......what am i doing wrong?

ty for reply. well, that is weird. had the usb formatted to exfat at first because they are big files then checked MS for xbox series x requirements and they clearly say "ntfs, MP4 and h.264"...........and yes, i run the videos through insta 360 programme then videoproc to stich and add transitions/music etc. Will try again with exfat etc though, maybe the box was having a bad day! lol

I also have this issue if you resolve it please post the steps.