Prolific messaging system broken?

Been trying to contact a researcher but it seems as if my messages haven't been going through (they have appeared in my sent though). Whenever I click send, I go straight to the 500 error page?

I've now had a study rejected because my original message didn't send properly which has kinda pissed me off. Been waiting for like 2-3 weeks for a study and finally get a good one and now this.

Is anyone else able to message any researcher?