Ugh. That's got to be a tough situation. Honestly I'd probably try sending them another note/ask thing just to see if they'd gotten/seen the other one. We kind of trust that onsite messaging systems are more reliable than things like emails that can get lost or sent to spam, but I've had people tell me that notes I send them (which show as sent and read in my outbox) never got to them. I don't know how Tumblr works though, and I'm also not really clear on how many notes have actually been sent.

I wouldn't think that a polite prodding would warrant a new policy like that, but it does sort of seem that way. I hope it gets cleared up and the artist responds at some point. :/