Similar issue for me as the OP. Installed iOS 11 on my iPad yesterday and Opera Mini will begin to load with the Opera logo and Speed Dial grid both visible on the top right as normal. But the buttons are unresponsive, no Speed Dial icons come up and the app just hangs for a few seconds and then switches itself off. I've tried uninstalling/reinstalling the app while retaining the data (as per the new iOS feature) and it still doesn't work. I haven't yet completely deleted the app as I don't want to lose my bookmarks etc.