I tried for the first time yesterday to split some 3 year old rounds of black ash and even a 20 inch long 8 inch round laughed at my X27. I just read through this thread https://www.hearth.com/talk/threads/split-now-or-in-spring.136250/ and it sounds like people process wood soon after it is cut. I am starting to think that by letting my ash dry I have just made more work for myself. When I did manage to get a split off with some wedges it is testing at 16 to 20% moisture. BTW I had to drive the wedges separately to keep from getting them stuck. In an 8 inch round it was drive a wedge out of sight along an edge then use a second wedge from the side of the round to finish the split and free both wedges. No way it should be this hard.
Don't know much about ash but all the wood I process is split the day it's dropped.
Once the ends get weathered splitting gets tougher.
I like to split from the bottom of the tree up. Less chance of trying to split a knot. I also
try to hit the middle of the round with the first strike. Oh yea the colder the better.
Everything gets piled and covered close to where it's dropped. Makes for less handling
of wet ( heavy) wood.
BTW check moisture after its been indoors (warm) then re-split. Cold wood will give you a false reading.