This now appears to be booking until 13th February 2021.
Unlike other ATG venues which are, currently, scheduled to return on 27th April, this isn't scheduled to recommence until 1st June.
When theatre is finally back, I can see this show doing extremely well again. It's message is very 'now'.
The Lion King (ATG) seems to be off sale until June too, despite the message on the show website saying 26th April.
My guess is that it's far easier right now to have tickets off sale until then, in case theatres are still closed come June. Otherwise, it's a whole load more customers to have to deal with in terms of refunding and, perhaps, disappointing.