Dargo, do you have an ETA to fixing the issue?
I don't have an ETA for when the issue will be fixed but I'll post an update here as soon as I have any relevant information. We have a system that limits withdrawal amounts if the funds are needed to back orders or margin positions (and other things). The bug is in this system since it is incorrectly withholding a portion of funds in some cases even if you don't have orders or margin positions. In most cases it only withholds small amounts and you can probably withdraw all or almost all of your funds by doing two withdrawals.
Although the issue isn't fixed yet, many clients who couldn't withdraw all their funds before may be able to do so now. If you go to Funding > Withdraw > Bitcoin and look at your maximum withdrawal amount, this should tell you whether you are able to withdraw all your bitcoin or not. The fix may take a few more days to complete, but hopefully not more than that.