With custom movement, you have to code it to consider something solid.
To do that, you need to set the stepping mode to what you want:
On PLAYER [STEP/HORIZONTAL STEP/VERTICAL STEP]<font size="1">Step is for Linear, Horiz/Vert Step is for the other 2</font>
Is overlapping OBJECT OR FAMILY
PLAYER Stop Stepping (Go Back a Step/Stay at current position)
<img src="http://i.imgur.com/1ecVbb6.png" border="0" />
I use custom movement because I have to have things pass over things other things consider solid, but still react with some of the solid objects as well.
Because of that, I was messing with it and found a few bugs that have been fixed and makes things work great. I recommend you to play around with it to, as the other movement plugins use the same basic functions that this provides.