If you were active within the 6 months leading up to the go-live date of April 7th and did not receive collector certification, there could be several reasons:
You're using a guest account.
Your account has been warned or suspended due to inappropriate behavior in trades.
Your account has been warned or suspended for card cycling.
Your account has been warned or suspended for cross trading.
Your account has been warned or suspended due to chargebacks.
Your account has been banned.
Your account has been warned, suspended, or banned for using multiple accounts on the same device.
Your account is not in good standing for any other reason not listed above.
If your situation doesn't match any of these, or you are unsure please reach out to support for further clarification.