Have been going back and forth with Escape on this issue. Have gotten a couple of acknowledgements of problems.
Grey tanks:
Note that this doesn't match my measurements or others that I've seen in this thread. We only measured 20 gallons of capacity on grey, a 27% reduction. Leaving the difference in measurements aside it seems at a minimum that the tank is not being installed with enough support across the middle.
Black:
So the black tank is not as large as advertised to me or anyone else who has purchased a 21NE. Instead of the 22 gallon tank that we were sold we received a 13.2 gallon tank, a 40% reduction. Their resolution is to update the website and to say there are no other options available. No communication to existing owners, no apology to this owner and no fix or restitution of any kind.