CC Value "forcing" when recording

Hey there. I’ve encountered a weird little thing, that drives me crazy!
I have two Hermod+ Midi Tracks sending Midi Note Data to Oxi Coral, multitimbral on two different Midi channels.
I also control the cutoff filters of both timbres via another midi controller, bypassing hermod+ for the control of the filters.

When I close the Cutoff CC via the other controller, the second I record something into one of the two Midi Tracks on Hermod+, the Filter of that timbre on Oxi Coral opens up full again. As if starting a recording on Hermod+ would force something to send a CC value of 127 to Oxi Coral’s filter.

So I added a Midihub, blocking Midi CC from Hermod+ to Oxi Coral via a midi Filter Pipeline. so in theory, no CC should even reach Coral directly from Hermod+
But it still does that. What else can I try?

I feel, it has to be something that Hermod+ does, becaus it happens everytime and exclusively as soon as i launch a recording on said midi Track on hermod.

Do you have any Ideas, what that could be?
Thanks for any hint here…