When your BUX Crypto account is migrated, you will notice that your BUX Crypto account is blocked. You should then see your crypto assets appear in your BUX Zero account.
If your crypto assets have been migrated to BUX Zero and they are not yet visable, this could be due to you never having made an initial deposit to your BUX Zero account. Depositing a small amount (even 1 Euro cent) should correct this issue. Alternatively please contact the BUX Zero support via the in app chat.