Since installation of Lightroom 6 shortly after it came out, it happens to me a couple of times that Lightroom doesn respond when I am switching catalogs.
I have solved it previously by un installing and re-installing the program, but clearly this is not a futureproof solution. Manually trying to open a different catalog doesn't work either.
Hi, I have the same problem, re- installing doesn't work for me either. Think its about time Adobe addressed this issue, its very frustrating.