You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
So I’ve updated my 2016 IPad Pro 9.7 to iOS 12, and now get the above error for the Apple Keyboard. Yet, It’ll work for 10 mins when I pick up in the morning yet never again.
I’ve cleaned, restarted, removed and re connected and all variations of those.
Any Apple-ists that can help me resolve it about?

Mine works 👍👽
Try forcing a reset - hold the power and home buttons until it restarts and you see the Apple logo. Not entirely sure how this differs from turning it off the usual way but it seemed to solve some issues with iPhones.
Take a look at the magnet suggestion in the first response here: https://discussions.apple.com/thread/7678022
I wonder if it would work on my iPad.
#ibsr