Hi there, yes same thing here. It's not only the "Retweet", the "Like" too. I mean, both the "Retweet" and "Like" actions are not taking place, if you are executing them from the iOS Notifications Center screen. If you do either action, you will not see the "Like" or "Retweet" on your Twitter Timeline.
I have already:
01. Removed the Twitter App, removed my account from Settings, restarted the iPhone, added my Twitter Account back, reinstalled the Twitter App;
- Did not worked. The issue is still there.
02. Reset Network Settings
- Apple Support account on Twitter advised me to do A- A "Reset All Settings", but i do not agree with that approach, further more, it will be very annoying to me so, what I did instead, was a "Reset Network Settings." and/or B- Contact Twitter Support which I did both via Tweet (no answer so far), and opening a Ticket on "https://support.twitter.com/forms" (no answer so far either).
iPhone 6s, iOS 9.3.2 (13F69)