Retrieving a user, ie from /1.1/users/show.json contains a “status” which lacks the usual “extended_entities” field.
It’s unclear whether this is a documentation oversight and a missing feature, or a bug. If it’s a missing feature, please consider adding it (and fixing the documentation in the mean time).
The documentation on https://dev.twitter.com/rest/public/uploading-media-multiple-photos implies, but doesn’t really state that this new field will be available uniformly. It would be a rather strange thing to intentionally remove it from /1.1/users/show.json status but leave it in the /1.1/statuses/show.json status. However the example on https://dev.twitter.com/rest/reference/get/users/show is missing the usual “extended_entities” field, so either that’s another oversight, or perhaps an intentional omission? (If intentional, it should really say so explicitly.)
Note that extended_entities is missing even in the case where the user’s most recent tweet would require it for correctness. In that case entities appears to contain the left-most or “first” image only.