When doubleclicking on the block the normal process happens, a dialog with the chords is been presented.
The only problem I have is that the chords don’t show anymore, they still are played back correctly but have to write them down to be able to play along.
Wow, that’s weird. If you haven’t yet you should submit a support request through My Steinberg.
If you have an older version of Cubase still installed, do they show up if you open it with that? If so that would imply that it is a problem with how 8.5 is displaying things. If not it suggests your cpr file is getting messed up. Of course neither of those really gets you anything.
While not even close to a work-around, drag all your chords down onto a dummy midi track. This should create a midi part for each chord that is named after the chord. Not easy to read, but still something.