[mbronze]

This solved me the 1080p stuttering problem:
Check Player Settings -> Video -> Processing section -> Set the 'Enable HQ scalers for scaling above' to 0% and turn off 'Allow hardware acceleration (Surface)'
(Don't forget to switch Settings to Expert mode first to find these options!)

This setting will give me poor scaling quality on my 4K tv and disable HDR. When I’m using 4k@60 resolution 1080p videos are mostly smooth with a slightly stutter, I guess thanks to the HQ scaler. But 4K stutters a lot. Are you only having this stutter only under @24hz resolution of box setting?  

 I was not quite observant, sorry for misleading!
My TV is not 4K, it's just FHD. (box resolution is 1080p 24 Hz, and no more stuttering with the above-mentioned settings)