25fps/ 50hz stutter

Hi I’m having an issue with 25fps video stuttering.
I have kodi 17.1, windows 10 anniversary update, intel core 2 duo 3 ghz, 5 gb ram, 64 bit os, radeon hd 6670 cataylst 15.7.1, hooked up to my tv through a pioneer AVR using hdmi.
I have an samsung LCD tv that supports 24hz.

I have enabled the refresh rate sync, and it works perfect for 23.976 fps and 24hz, it switches and playback is smooth,
but when I play 25 fps video, it switches to 50 hz and there is an occasional stutter.
I’ve tried fiddling with settings and cant get anything to work. I might try setting up an external player and see if that works.
anyone else have this problem and have fixed it? I can’t seem to find another other threads that have the exact problem.