Bitstamp reply my ticket:"thank you for reaching out.
We have received your withdrawal request which is currently pending to be further processed on our end.
Due to current surge in demand, SEPA and wire withdrawals are taking extra time to process.
Please rest assured that we strive to process all requests as soon as possible. In case any additional information from you will be required, we will contact you via our support ticket system.
Thank you for your patience and understanding.
Should you have any additional questions in the meantime, please do not hesitate to ask."
https://www.reddit.com/r/Bitstamp/comments/7jrdob/post_here_if_fiat_withdrawal_succeeded/
Well it's exactly what they said. They either have a huge problem with their backend in terms of banking system not allowing them to keep accounts with them anymore for the purposes of dealing with cryptos(like bitfinex), or it's what they stated, there is just a surge of demand in terms of cashouts that doesn't allow them to process your particular withdrawal quickly enough.
Either way, nothing you can do about it really to help the situation.
Just remind them if they forget to contact you and wait. Bitstamp is a regulated exchange so they wouldn't just exit scam.