Major MAJOR movement issues

I'm using a custom tileset (I didn't make it).
I've set the movement permission etc, and I've added the priority of things to walk behind +1.
But now, any map I'm in with this custom tileset, it won't let me move from the spot I warped to. I can look around, but not move.
Help?

1. I've made the grass walkable.
2. I've made ALL terrain walkable.
3. I've made sure none of the warps warp to another warp spot.

The most likely suspect is that you used a blank tile (other than the upper-left-most tile) to erase with.

Here's a little trick I like to use with custom tilesets.
Open the tileset in an image editor that supports transparency (Not Paint)
Put a red dot, or red X in all of the blank tiles.
Save the file, and go back to your project.

Now if your map has any red dots or X's, find the layer they're on & erase them with the upper-left blank tile.

As far as I'm concerned I haven't erased layers with other white squares, but I'll do what you suggested to check anyway.