I also have a legacy account, it's empty and I haven't used it for a while but was recently thinking of doing so, now I'm not so sure.
At which point did you discover your account was disabled, when attempting a deposit, withdrawal or trade?
It was when I went to generate a deposit address for a coin. It fails with a pop-up saying account disabled. I contacted support and they said they would not enable my account until I did the verification.
I wonder if new accounts also have to do verification if they're only trading cryptocurrency.
It would seem that they do, at least when it comes to withdrawal.
Withdraw Limits - Unverified Accounts created on or after 08/01/17: 0 BTC (or equivalent) per day