I use the input filter quite a bit on the “channel Settings” window. I have been finding that after closing a session and reopening a session, some of the tracks are not filtering out the high and low frequencies I have set in the settings. After I touch a nob a little it wakes up and starts working again. I have only just noticed this issue about a month ago. It may have been happening for a while and I just didn’t catch it. I have not found any kind of differential in regards to the type of tracks. I have noticed it mostly on audio tracks that I clean up after recording or rendering.
Make sure you have the latest Cubase 9.5.30 installed, please.
If it still doesn’t work after the update… Could you specify the affected tracks? Is it one track type (for example all Groups)? What have the tracks in common?
I’m getting this too https://www.steinberg.net/forums/viewtopic.php?f=253&t=145080&p=780984#p780984
And, a longer thread here. https://www.steinberg.net/forums/viewtopic.php?f=253&t=140981