I have had the same problem, used to receive a few email notifications every other week with what was new, haven't had any for the best part of a month I would say.

There was a couple of new tartan's logged today, you can see a stream of the new additions here: http://www.tartanregister.gov.uk/whatsNew.aspx

I'll try to contact them too, if they hear a few people are having problems I'm sure they will look into it.