It should wick fine. 
It might work better if you "dunk" the foam into the liquid in the cart. If it is saturated, it may work better. I cut mine the same width as the cartridge. Folded my 1/2 inch piece in half, dunked it, pulled it out to add more liquid to the cartridge since the blue foam soaks up a bunch, stuck it back in and vaped away. If it doesn't wick well it is most likely too thick or too long. You only need a small piece to "plug" the juice filled cart. 
It can be a pain for many, but once you figure it out it usually satisfies most users. 
I wouldn't have recommended it after trying all those types of filters if I didn't believe in it. 
It really does a great job if you can figure it out. 
I had a video around somewhere on an old youtube account.