If you have fiat A in total and issue buy all with btc B(auto calculated by the system) on price C.
A = B * C, trading fee is not deducted from this calculation.
Therefore, if your buy all order get filled with one trade, you will owe bitfinex trading fee, that means negative balance in fiat. The system will immediately issue settlement by deducting some btc from you account, that amount of btc equals to the trading fee of your order(the btc amount deducted = trading fee / the lowest current ask order). The corresponding settlement order can be found in trade history, just right after of your buy all order transaction.
If your buy all order are partially filled with multiple trades, the order will get eventually cancelled just like your case.
For all the case, you don't lost money. Bitfinex support doesn't answer all emails, this makes customers felt bad.
If I remember it correctly, it got dumped with a big sell order. Same with the test I did.
If it got filled with multiple orders, isn't it going to appear on my log?
Here's the log from the test I did:
From my USD log, they converted all my fiat to btc, deduct the remaining $0.0178xxx to the fee and then gave me a negative balance for the fees.
From my BTC log, they sold a small part of my btc to pay for the fee.