The problem is that we ran out of money.
We don't keep a lot of money on exchanges, for the obvious reason. Normally, it would be easy to send more money to Coinbase, but in this case, Coinbase is requiring 3 days of confirmations for ETC.
The confirmations are an obsolete reaction to a 51% attack that was conducted using NiceHash against the ETC network 15 months ago. Since then, the price of ETC rose by a factor of 5, and the network's hashrate also significantly increased, making the large number of confirmations unnecessary. Nevertheless, for an unknown reason, Coinbase still requires them.