Sometimes it is best to take a breather. Walk away from it, give it some thought and go right back at it.
Like Steve said it may not be you,it might be(most likely) the stone. You are used to 20k and not all jnats are at that level. When you find one, trust me you know.
Arkies are hard to master, so are Jnats and Cotocules. When the right technique is applied to each individual stone then you can squeeze every last bit out of your stone.
After honing with many different types of stones you get a feeling of what works better on a given stone but you should always try a couple of techniques on each stone.
A microscope or quality optics go a long way in helping you determine what you are feeling in the test shave.