Are there any updates on this?
Trying to send any image via UIActivityViewController results in the image not populating in the Twitter compose dialog, and attempting sending the tweet generates “Tweet failed to send”. While it claims there’s a draft there isn’t.
The image being used was only 55KB.
Sending just text works fine.
This is with Twitter 7.9 installed, Xcode 9.0.1 and iOS11.0.3.