Stark contrast to some assertions that MS were effectively lying about their UHD support and shouldn't be allowed to sell the console on such grounds because it couldn't play a lot of discs.
I assume that was with the first few roll out attempts of 4K BR with all the changes. Same thing happened with HD DVD/BR for a while until players and authoring became more consistent. I pay little attention to "hobbyists" and generally wait for a summation from trusted sources.