[noggin]

30hz isnt a standard, so good luck finding a Tv that supports this mode. 23.976/24hz wasnt a standard till pretty late in the plasma age, when the second/third gen. Blu ray players began to appear with support for 24hz. Pioneer tripped the framerate so internally it was running at 72hz, Panasonic went with 96hz in their top models. Cinemas from used to run at 48hz). This was using plasmas, lcd does not flicker so one does not need to process the vertical sync @ 3 or 4 times.

Point is, 60hz is already a standard which is integer compatible with 30hz, so there was never a need for 30hz. It would be totally and utter pointless.

Even if your display supported both 30 and 60hz, the 60hz mode would be preferable. No blanking, smoother gui when going out/in of fullscreen. So when Kodi is using 60hz with your 30fps movie, it is doing everything correctly. This type of question pops up far too frequently. If only people could think for 1 second: Hmm, I wonder what the freaking *point* of "adjust display refresh..." is....?

2160/30p (and 2160/25p) are both standards for HDMI 1.4a (as 2160/50p and 2160/60p aren't supported on HDMI 1.x variants - though 4:2:0 2160/50p and 60p is within HDMI 1.4 bandwidths ).

720/25p, 720/29.97p, 720/30p, 1080/25p, 1080/29.97p and 1080/30p are all CEA 861 supported formats (and I believe at least one of my displays supports them and flags them via EDID) - though there is no need to use them over the 50/59.94/60p variants (unless you have bandwidth constraints)