We are seeing since a couple of hours ago how trying to post more than one user on the user_id parameter for the above mentioned endpoint (add_user.json) fail to add more than one user per call.
This was working fine up until a few hours ago, we had to change our code so it’ll add one user per call.
Any change on your end that could be causing this?
According to the docs (https://dev.twitter.com/docs/streaming-apis/streams/site/control#add) we should be able (and we were) to post up to 100 users per call.