Who designed their system to require ALL multi-signature keys to sign instead of a majority? Talk about one of the stupidest decisions I've read about this year.
Suppose one got hit by a car, are all of OKEx's funds lost?
Perhaps this is just another exit scam. It always bears repeating, but if you aren't trading, don't leave bitcoins on an exchange, you don't own them, you are just a creditor. And a creditor if you are lucky and it isn't a scam.
https://cointelegraph.com/news/btc-and-okb-plunge-after-okex-suspends-withdrawals