The problem is that they did not let everyone withdraw due to verification issues.
WEX can't allow unverified fiat withdraws because of AML and KYC laws.
As far as I understood from their news articles, BTC-e used a 3rd. party verification provider.
For some reason WEX had to find another verification provider probably to meet the EU KYC standards.
The new verification provider wouldn't have access to the old BTC-e verification providers data, so users have to verify again.
Moral of story, don't withdraw fiat.