Question Animation's Child Transform Position is Wrong?

Hi everyone!

I tried animating a character and a carriable object so that I change the transform component of the carriable to follow the hand of the character. This seems to work as intended when I preview it in the animation window, but after pressing play, the carriable seems to be in wrong position, and it also looks like there's some kind of interpolation happening between the frames. Animation in Play Mode has been slowed down to see what's happening.

All the tangents in the curve editor have been set to constant.

Anyone have any idea why this might be happening?

Here's a video showcasing the problem:
https://www.dropbox.com/s/ltm4cy0k629j5gn/Carriable Animation Problem.mp4?dl=0