Oh dear, we're sorry! Can you swipe left in the app for Settings > Advanced > Reset Local Cache to see if that helps? 
@SlackHQ these photos have been hanging... perpetually loading since yesterday. How to get rid? Won't let me delete?pic.twitter.com/33kvirJzvx
-
-
-
fixed. Thank you.
-
Fantastic! Thanks ever so much for letting us know.
End of conversation
New conversation -
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.