Try wicking without thinning anything from the center of the rayon. Perhaps you are thinning too much and the rayon is not as tight in the coil as it should be. If you thin too much your wick will contract more than it should and that could be the reason for them frying in the center.
If the folks on YT are pulling their rayon wicks through their coils freely, they are not using enough rayon. Rayon should not freely move through a coil. It needs to be tighter than you think.
See the official rayon thread, everything I've posted can be found there.
This is a continuation of the ground breaking Rayon Wick - better flow, flavor, saturation, and nic hit!! thread. The Rayon revolution started here on ecf when I introduced its amazing properties and those first few users returned thier...
www.e-cigarette-forum.com
The wick you posted a photo of looks like it's burnt in the center. Try more rayon.