1. Open orders on the exchange, and
2. Pending move/withdraw transactions that have not yet executed. These transactions get auto-cancelled by default after 24 hours. You can change this behavior at Wallets -> Cron job -> Cancel old unconfirmed/pending transactions.
But the problem is, when a user submits a withdraw request for a fiat coin, and I go to ‘tools->fiat withdrawals’ to mark the transaction as ‘done’, it shows the error: Cannot withdraw 10.000000 EUR because only 0.000000 is available.
The problem is… the user does not have any pending orders on the exchange.
So how can one perform a fiat coin withdrawal? or is there a withdrawal shortcode made specifically for fiat coins?
The withdrawal shortcode for fiat coins is [wallets_fiat_withdraw].
If you have set up fixer.io access correctly, you should not be able to see the fiat coins in the standard [wallets_withdraw] shortcode.
You mentioned that the user does not have open orders on the exchange. Did you also check for pending transactions? You can go to Wallets -> User Balances to verify if the user has enough total and available balance for each coin.