How to react to a started clip recording?

I want to set some parameters as soon as a clip started recording.
So I store the clip id and track id in modifiers.

I created a second reaction and added a listener:

self.song().tracks[self.get_modifier_value("m1")].clip_slots[self.get_modifier_value("m2")].clip.add_is_recording_listener


This reaction never gets fired. I believe that using modifiers doesn’t work with listeners. So why can I use modifiers for listeners?

I also tried to add a listener that fires as soon as the clips of a track changed:

self.song().tracks[0].add_clip_slots_listener


This also never fires..
Can someone confirm that behaviour?