Yay, finally official word from someone who works at Line 6...
Dear Line6, ask your iOS developer(s) about expedited reviews. When you have a bug of this nature you can ask to jump ahead of the review queue — especially when its affecting now irate customers.
This inconvenience is far from over. It certainly has caused lots of inconvenience and continues to do so by your inaction.
sdzimmerman had a great suggestion above — how about using TestFlight with some customers to get test your fix with real customers? Some transparency and visible progress would be very welcome.
This is not how you treat paying customers.