I haven't been mining on Middlecoin (except when my other pool goes down) for about 2 weeks and there is about 0.0035Btc that seems to have been stuck since then, some of that is new, but the majority is over 2 weeks old. As I write this there is 0.00197542 immature, and 0.00161261 unexchanged.
I see the bug. I'll be looking at this in the next few days. Looks like there's as much as 3 bitcoins total worth of stuck immature funds.