I have been searching for ways to filter MIDI messages.
My synth sends way to many CC123 "all notes off" messages, and I started building a filter in Max for Live, when I noticed the message passes through the Max for Live plugin even when no connection is made:

This is the MIDI plugin template from Max for Live itself with the connection between input and output removed. Am I doing something wrong here? Is this expected behaviour? This is Live 10.1.9 with Max for Live 8.1.1.
Thanks for any help!
PS: This issue seems common with some old synths as input - e.g. viewtopic.php?f=2&t=174537
PPS: I currently work with a workaround using a VST MIDI plugin, but this is far from elegant, and crashes Live when I close it...