Strange movement with Platform behaviour

I'm having troubles with the Platform behaviour on one of my objects. I have a Player object with the platform behaviour on it, and it's colliding with a Ground object with the Solid behaviour. I also checked the "Optimize for Pixel Art" option when I created the project, which could be relevant.

However, the collision is not at all what I expected. The Player object seems to hover a few pixels off the ground, and does some rubber banding if I try to move into the side of the Ground object.

Here's a link to my Player's collision polygon, as well as a couple GIFs displaying what happens between the Player and the Ground (the Ground's polygon is default):

imgur.com/a/VcNJwWH

Why is this happening? Is there a setting I should change, or should I be avoiding the Platform behaviour?

Is the collision box of all you frames the same? Did you set the origin of all your frames to the bottom? Also try to use an invisible sprite to move the player sprite. This is much more glitch free. You can do it like the 'Kiwi Story' game demo in C3 start page.

Is the collision box of all you frames the same?

This is the answer. I just assumed that the collision polygon covered all frames, so thanks for that.

I will check out Kiwi Story when I wake up, will come back if I'm still having problems.