A coworker tried to enroll on arrival at O'hare recently and was told its no longer available, everyone has to go to the custom's office now
At the end of last month they were still doing EOA at ORD.
Did the co-worker fly into ORD from a CBP preclearanace airport or on a weekend? CBP’s EOA page still has EOA listed for operation at ORD at counter 58 in terminal 5 with its limited hours of operations for Monday to Friday.