Header says it all. Numbers of people reporting custom channels are gone and you can't recreate them again either.
In case it helps, not all players have problems, I was able to speak to the Homeshow channel on AB and Storms channel on Thurg (from Test) and people answered there from live servers. (that is before Test patch)
I'm on Maj'dul and the problem appears to be widespread according to a number of people I've talked with. Some channels don't seem to be affected, but others created in the last 2-3 years have all gone and you can't create new ones with any name.
I now know what the problem is, although I don't recall ever seeing it "announced" or posted anywhere on the forums. Apparently, only custom channels using alpha characters are now allowed. Any channel using numeric or other special characters was eliminated, nor can you create a new one using those.