I believe your attempt to take the offer wasn’t successful so your funds didn’t ever leave your wallet. You can check if under FUNDS > TRANSACTIONS you’ve had any transactions related to this trade.
You are correct, the funds never left the wallet. However, I have a frozen transaction I cannot remove, which didn’t even reach phase 1 (Wait for blockchain confirmation), while the buyer informed me they have a similar situation, although their transaction reached phase 1.
Make a backup and use the ‘BTC wallet emergency tool’ by pressing ctrl/cmd+e. Verify that the amount you’ll be sending includes the amount reserved. I think that by withdrawing to an used address from the FUNDS > RECEIVE FUNDS it should unlock the Reserved funds.