Choppy 60p footage

[Viktor Rjabkov]

Timeline 30p, Video filmed with 60p, slowing down 50% = getting choppy video ???

Can someone please explain this to me ?

–I am using fcpx(10.6.2) on an fullbuild iMac 2017 so this shouldn be a problem.

-Timeline settings:

3840×2160 30p / Apple ProRes 422

-Clip: 3840×2160 59.94p

recorded on a NinjaV from a Sonya7siii in ProRes

So why does slowing down my clip by 50% results in a choppy playback, as if it was filmed only in 30p

??

i am very thankful for any tips, thank you!