@Katie---Sean0 I've read a few posts here lately saying the same thing, but I haven't experienced the issue. What I did notice is that they changed the box that used to say Available and Blocked, and now it just says Available with a toggle to turn that on or off.
But I can still click on a date, drag and unclick on the last date, then click the Available button off.
However, it didn't look like those dates were highlighted when I dragged through them, as it used to. But they did block when I then turned Available off. This might be what's confusing you.