I was testing out the beta search and found that the 'Category' widget isn't working when the query is set to 'Use Group'. All results are returned (as opposed to just the group items when beta search is not enabled.) It also looks like pages aren't returned as results yet either.
Thanks for working on improving the search!
Sorry to drop the ball on this, but just wanted to let you know that the group query bug has been fixed. We're also out of beta now so you should be seeing the new search across the platform.