Me having the same issue here. I tried to withdral a couple of ETH from Poloniex while everbody has ico-cash-signs in there eyes ... meaning 2017-06-20 at 9 PM... I recieved a Complete from poloniex in my deposit & withdrawl history with an txid, which is impossible to find on any explorer. Poloniex itself does not respond to my support-ticket for almost 2 days now.

Here is what i found out about it:

##IN SHORT##

The status-ico clogged up the network with a gigantic number of high-gas-fee-transactions, preventing normal tx's from getting through (because their lower fees lead to lower priority by miners).

Now the ICO is over, but there are still a huge load of transaction clogging the network. At the moment just transactions with an high fee gets processed properly (wich no exchange pays freely). So a ton load of people are missing their money.

So everyone reading this: Be acarefull withdrawling any ETH or ETH-based Tokens from any exchanges - get information if they are handling the problem properly!!!

##MOREOVER##

To have a feeling about how many tx‘s there had been, see this graph, showing the amount of transactions per hour that the Ethereum network processed since a few months ago:

https://www.reddit.com/r/ethereum/comments/6ig70p/ico_traffic/

„Furthermore, evidence is accumulating that f2pool was actively manipulating transactions bound for the Status ICO, which they participated in themselves, exacerbating the problem. Experts explained weeks ago that bad ICO designs are vulnerable to such attacks, but this appears to be the first time it was actually executed in the wild.“

https://www.reddit.com/r/ethereum/comments/6imd5u/can_we_make_a_mega_thread_for_people_to_explain/dj7eq1w/

Some more detailed information about the claims are given here …

https://www.reddit.com/r/ethereum/comments/6itye9/collecting_information_about_f2pool/

This ICO‘s are destroying the integrity of the whole system but all people just have dollar-signs in their eyes. This madness has to be stoped!

It will be very interessing ( ... for me maybe just frustrating) how all the websites will react, which have to handle this problem ...