They encountered some issues with v6.1, and they are still taking their time to fix everything.
There is no concrete release date, but I’d guess it will be within the next 1–3 months.
What’s coming:
ATS v6.1 with improvements and new features, such as the higher time frame trend line displayed on lower time frames
ATS v6.1 Assistant
ATS v6.1 for MT5 as well