OpenWRT on master is not for the timid - moving target as things tend to change there often, and don't have the QA that a Release would.
Keep in mind that both QCA and MediaTek use OpenWRT as a basis for their SDK's, but it's loosely related to the openwrt, and the SDK's have proprietary support that isn't generally backported in.
MediaTek has been fairly active there, compared to others - but I still wouldn't recommend snapshot builds for day-to-day connectivity...
I would stay with the GL-Inet releases for MT6000 for the time being...