I have same issue here, I transferred ETH to my METAMASK yesterday. The funds were debited from OKEX account, but did not appear on my METAMASK Wallet.
On OKEX:
Select currency
ETH
Withdrawal method
On-Chain
Select the USDT withdrawal network
ETHK-OKExChain
On METAMASK:
I simply copied the public address.
Note: Under the “Wallet” stands “Ethereum Main Network”.
After that I submitted it. And still no ETH on my wallet. Could you please help me?