When bridging ERC20 tokens, an approval must first be given to the bridge contract before the bridge can be initiated.
With tokens like USDT, TRAC, MASQ and a few others, an intricacy is present in the smart contract where approvals can't be altered unless the existing allowance is zero.
In the rare instance that you have previously approved the bridge contract with an amount smaller than you're currently bridging, Superbridge will first prompt you to revoke (set to zero) the existing approval, then you'll be able to approve the amount you wish to bridge and proceed as normal.
If you're running into problems with this we'd recommend using something like Revoke.Cash to zero out your approvals. After doing this you should be able to bridge via Superbridge without issues.