TouchBar configuration failing in Xcode 9

Dear all,


I have recently updated to Xcode 9 via the AppStore.

I have a 2016 15" MacBook Pro with macOS Sierra 10.12.6.


Since then I have noticed, while using a playground, that the TouchBar was strangely less populated than normal.

Going to View and Customise TouchBar I get greeted with the usual editing screen but, instead of finding all the possible icons, I find many icons with an exclamation mark and the title "Missing Label".


Could anyone help me figuring out what may have happened and how may I solve this issue?


Thanks


Michele