As expected, it dumped hard. "Amazingly" IB is now allowing trading on this product again - but not before everyone missed out on that trade. Note: the "allows new positions part" is approximate, as I haven't been trying it every day or anything, but it did work last night.
I tried to contact several departments to find out the reasons but they never replied. I closed my account and moved to Saxo.
I just find it amazing/suspicious how the contract hit a key level, then suddenly no one can open new positions when rolling to the next dec contract, it dumps hard, then everything is normal with trading allowed again.