I previously had this issue. It only affects admins who have the rights to change the order of the pinned topics which is why it's unlikely others can't reproduce on the OPs site.
However since 1.7 (could be Chrome 64) I no longer have the problem.
Some bugs on mobile
- Avatars not showing.
- Youtube videos are Bigger.
- Chat window its too big, i cant close it.
No notifications and chats buttons.
@julian Reported !