Hi!
Nothing is broken here. It’s the way Cubase handle midi vs synth track. Its kind of bad implementation though.
If you select a midi track connect to synth “e” edit and open the midi specifications of the midi track.
If you are on selected audio-synth track “e” edit and open normal settings you want to edit example EQ, inserts etc.
Steinberg should program Cubase so “e” open always the linked synth audio setting even if you have selected a midi track.
Best Regards
Freddie