Claude did the same thing to me the other day. I ran out of my 5 hr limit, and it went into my $100 credit they had given me. Multiple parallel agents. It ate it in no time flat.

When I checked, all that credit was gone, I still wasn't into the next 5 hours, and all the agents had failed, returning nothing.

I didn't even get anything for burning all that credit. If I had paid for it, I'd be very, very pissed.