Browse Host isn't reliable. One minute it will work, the next it won't.
You're most likely to have success if you browse somebody who has chat enabled. You'll see a smiley in the chat column. If you don't have a chat column showing, right click on the column header of the search page & uploads window > tick chat. You should also have chat enabled

Try right clicking on a file > browse host, as well as using the Browse Host button. You'll have the best chance of success if you try to browse LW & FrostWire (Snow) hosts.
Just keep trying!