Did you read the same blue post I did? The blue post clearly says that they fixed a bug and that the current (fixed) 1.13.3 version is now accurate to 1.12:
A secondary effect of these fixes were two notable changes to Reckoning:
- Reckoning stacks are lost when you mount up.
- Reckoning stacks are lost when you initiate an auto-attack against a target and cancel it before it goes off.
However, both of these behaviors were correct behaviors in the 1.12 reference client and as such are considered bug fixes. Both of these issues have been added to the “Not A Bug” list.
Here’s the link to the blue post in question: Reckoning after yesterday's patch - #123 by Aggrend-1483
Sure enough: