New Roblox IKControl Instance doesn't come out as expected

I’m rigging a character model with the IKControl. It’s basically an R15 character rigged to an R6 character.

So, it looks like this.

But after walking around a little bit, I’m surprised with this.

I have tried everything, and this always happens. if any of you could help me out with this, it would be much appreciated.

I can conform this might be a world-space problem because it only occurs when I walk in a specific direction.