Now on live servers and on the War Within Beta, addons can no longer track exact Mythic+ count in Mythic+ dungeons.
If you used any Mythic+ addons in such as Angry Keystones or Reloe's Mythic+ Timer Weakaura, you'd probably have noticed two options for mob count:
The entries for mob count in the database haven't changed in The War Within — mob count is still tracked as an integer (e.g. 4) and the total count needed to complete the objective is also an integer (e.g. 300). However, the current mob count integer is no longer available for addons to pick up and now addons can only pick up the percentage count and the total count integer. This means that without a lot of extra work, players will need to get used to tracking and remembering mob count percentages going forward…
A workaround has been developed by Reloe's M+ Timer weakaura though, but it has more potential to break or fail in the case of a disconnect, zoning out of a dungeon or reloading UI. It also requires the mob count from the MDT Addon, meaning this addon must be installed. This Weakaura tracks when units dies and grabs the mob count from the MDT addon to keep an up to date current mob count tally that can be shown.
In theory, this shouldn't make too much of a difference, but it's a pretty annoying inconvenience for something that was once in a game. An integer value is always going to be easier to remember than a percentage and for those who try to do routes or have to make up count at the end of the dungeon, you're likely going to have to remember a few more numbers or have a few more addons.