IT does happen, often*. It only works with ltc to btc. The coins are sitting on the ltc block, in a btc address with 10 confirmation. Unfortunately multisig addresses both start with a 3. Bitfinex uses multi-sig deposit addresses. This is needs to be changed by the devs. It is an issue with the ltc client.
What does the txid refer to?
*https://litecointalk.org/index.php?PHPSESSID=o4dprt1jkfdousqhgo709imto2&topic=26513.15