split screen greyed out

I am working in Resolve 17.1 Studio
I want to 'on' split screen in te View menu, but it is greyed out.
How come and how do I resolve this?
I think it has something to do with primary and secondary screen or with clean feed but I am not sure and already tried out multiple possible solutions.
I want to 'on' split screen in te View menu, but it is greyed out.
How come and how do I resolve this?
I think it has something to do with primary and secondary screen or with clean feed but I am not sure and already tried out multiple possible solutions.