Sidechain inputs not showing

For some reason all of a sudden I don’t get the sidecahin inputs anymore.

I created a new FX track and inserted the standard cubase compressor.
I enabled the sidechain input but now when I select the output tab (or send routing tab) on another track the sidechain input doesn’t show up.

Has anyone had this problem before?

Same here. I have this issue with all Fabfilter VST 3 plugins. Sometimes a restart of the project solves the issuse, sometimes not. It’s kind of random…