About a month ago, the Mythic+ rewards track was updated to scale all the way up to +18 keystones, granting Myth 4/6 gear. Players tested this and confirmed the reward track on the Beta, but in today's Midnight Beta build, the extra track above +10 has now been removed, making +10 keystones the cap for Mythic+ gear rewards once again.
Keystone LevelGreat Vault iLvl
Datamined chart by Wowhead
2259 (Hero 1/6)
3259 (Hero 1/6)
4263 (Hero 2/6)
5263 (Hero 2/6)
6266 (Hero 3/6)
7269 (Hero 4/6)
8269 (Hero 4/6)
9269 (Hero 4/6)
10+272 (Myth 1/6)
Many players expected this to be part of the increased rewards for high level dungeoneers, with the assumed removal of the Deathless achievement and run which awarded another piece of Myth track gear per week.
