Even if two players stand in the same position and swing at each other, some reckoning swings would not be granted. Even if there weren’t any parries, dodges, misses or blocks. Even if there is no sitting.
You can see this happen with the second crit in this video: https://www.youtube.com/watch?v=nC8OXHrgSB4
You can see that the first time I get crit, reckoning works, but the second time it does not.
This is with 5/5 points in reckoning.
edit: This may be due to the fix to stop people abusing start/stop attack macros. If there is a side effect to the solution, which causes the talent not to work as intended, i believe that the effect is a bug and that the solution is not complete.
My brother quit because of this problem