I reset the Master for a track, and now I get 'Undef' as both Mode and Key

Hi folks,
So, after one day of owning an OP-Z I discovered that you can delete all your Master settings by pressing the Rec + Stop key for a bit. Yay.
However, I now have a completely blank Master Key and Mode with nothing but ‘Undef’ below them on the iPad. Any clues how I get the OP-Z to re-analyze my track and come up with something more useful?

Many thanks for any pointers!

Never mind. If you switch project and then go back to the original project it fixes itself!