I am looking for a way to display fields only when others are no longer empty. This does not seem to work with the current ‘When’ condition. Ideally, the condition should be negated, e.g. with an exclamation mark. I would appreciate a tip.
That is indeed not possible. There was a plugin for Kirby 3 called “Whenquery”, not sure if it is compatible with Kirby 4: GitHub - rasteiner/k3-whenquery: Conditionally show fields and sections. Better., maybe test if it works with K4, or you could use it as a starting point.