First, Check the choke's pin pairs . If there is no pin pairs for the choke, please set it first(Edit-Pin Pairs-Create Pin pairs...).
Secondly, You may have to delete the differatianl pairs to make Enets ,then re-assign those ENet differatial pairs.
Thank you, Yanfeng! You were right, and I did have to break up the diff pairs to get the enets correctly.
For completeness, I should add that the menuitem in the Edit menu was disabled, so I had to right-click the part number and choose "Create Pin Pairs".