I have the same issue. I can't get PM's but I can send them. Or at least, that's what I thought.
As it turns out, I opened my email, and there were a whole bunch of emails saying I had gotten PM's. So I opened them up and I can read them on my email. But if I click the link that says read the original message here or reply to the original message, whichever it is, I get sent to a page on the FH forum saying I can't reply to a PM that isn't mine or doesn't exist.