If a MIDI message is turning off the motion sequence button, then here are some possible documented ways for that to happen:

1) Motion Seq Button Off
SYSEX: F0 43 10 7F 1C 02 30 48 00 00 F7
This would turn the button off. NOTE: are you sure this is not somehow "recorded" in your cubase MIDI data? Can you "start over" - if not already doing this as a sanity step?

2) Reset all controllers (turns the button off)
CC: 79 (hex, or 121 decimal) w/data=0
Would also turn the assignable functions off - so you can test for this by making sure [ASSIGN 1] and [ASSIGN 2] switches are latched (not momentary) - and turn them both on. You'll see these also go OFF along with the Motion Seq button - which would be a clue that this is more likely the cause.

I'm not sure if there are any cases where Cubase would send a CC 0x79 - or has a configuration item to turn on/off resetting all controllers under different conditions.

Again, in order to diagnose this I saw this kind of thing I'd use a MIDI monitor, force the failure, then go back to the MIDI monitor and search for either of the two above messages to see if the DAW was sending a message to turn off the Motion Seq button.

Hi Jason, thank you, sounds pretty complicated but I´ll try to understand and try your suggestions. I guess there is no easy way with midi.

I guess there is no easy way with midi.

This, of course, begs the question: Why are you recording your additional track, the one with the Motion Sequence as MIDI?

It is highly unlikely either one of the principle reasons to Record as MIDI are in play:
1) You are going to notate the data in the Score function
2) You are going to edit the events in Cubase.

The reason I say this is because editing a Motion Sequence is more likely, more easily done by editing the Motion Sequence parameters in the Montage... versus the after-the-fact editing in the DAW. Like overdubbing an electric guitar or a vocal, try recording as Audio... just saying. If you don't have a MIDI Jedi Merit badge, navigating the deeper waters of MIDI can be daunting.

Sorry, just had to point that out first. Without seeing or being provided more information about your previous recorded MIDI tracks, its virtually impossible to tell you why you are getting the reaction you are getting. You don't mention how many Parts are involved.

Wild guess (based on the slim amount of info given):
Try rendering the first three tracks you've recorded as MIDI data to Audio Tracks. This way you get to use your Montage's full power to execute your Motion Sequence. I'm beginning to think you have three Parts attempting to playback MIDI data while simultaneously attempting to manipulate a Multi Part Performance with a Motion Sequence (but this is impossible to know from here).

The Montage workflow is likely to require MIDI and Audio at some point.

Can you provide more info, please...

Hi Bad Mister.
The reason I´m recording in midi and not rendering to audio because the song is just a beginning idea and not ready to render yet. So I thought I´d stick to midi for every additional track until I have a finished song structure. There were 3 parts in the performance, 1 bass arp, 1 drum arp and a melody. I recorded those to 1 track, then split that track up into 3. Then I added a forth part to the performance with a motion sequence and wanted to record this in midi to track 4.

But I guess rendering the other, unfinshed tracks to temporary audio and recording the motion sequence as audio will save me some headaches. I thought as long as the song is not finished keep everything midi but that´s probably a bad idea after all.

It could be more complicated. There's a pretty simple test to see if for some reason the problem is related to a controller reset or not. This is functional testing without diving into MIDI - just "arm" your [ASSIGN 1] button so it stays lit - and see if it turns off like your motion seq button.

Looking at MIDI messages is more direct - I gave two things to look for. At least it's not 20 (in other words: could be worse).

There's no requirement, though, to learn more about MIDI if you find a path that serves your needs and avoids diving.

Hi Jason, yes assign button 1 also goes off when I record, after a few seconds, but not at the same time as the motion sequence button. So I suppose Cubase is sending off messages. But I don´t understand what I´m supposed to do about that now.
Not only that, I cannot turn the assign 1 button off anymore either. I guess my setup is still not right. Will it ever be? It would really be nice, after all these months trying to set up Cubase and Montage and dealing with one midi problem after the next, to get this right once and for all and finally have the time to make some music....

maybe the montage is just too much for me 🙁 in the past I hardly ever recorded midi, just audio. I think I´m too stupid for this. pretty depressed right now.

https://yamahasynth.com/forum/local-control-off-super-knob-lock-up-no-movement#reply-17813

Under cubase, check:

Menu: "File" -> Sub menu "Preferences...."

Popup window, find:

MIDI
--MIDI File
--MIDI Filter

Click on "MIDI" (the first one = main category of preferences)

On the right hand of the screen you'll see

"Reset on stop" - make sure that is not checked.

You'll see "Insert Reset Events after Record" - make sure that is not checked

I have "Never Reset Chased Controllers" unchecked - but you can check it to be paranoid about reset events.

Of course - "MIDI Thru Active" is checked to make the whole thing work (which I have been using a layman term "echo")

I'm not sure if you mentioned using Cubase 9 or not - since I only have Cubase AI 8.0 - there may be more things to check under 9 or additional "gotcha's".

Under the next sub-category "MIDI File", I have "Export Automation" unchecked "Export Inserts" unchecked "Export Markers" unchecked "Locator Range" unchecked. This is "extra stuff" that could foul up the Montage - although many of these should be fine - you may not want to filter "Export Automation" and "Export Inserts".

FYI (documentation backup information):
https://steinberg.help/cubase_ai_le_elements/v9/en/cubase_nuendo/topics/preferences/preferences_midi_r.html
https://steinberg.help/cubase_ai_le_elements/v9/en/cubase_nuendo/topics/preferences/preferences_midi_midi_file_export_options_r.html

Even though above shows "v9" - applies equally to v8 for items mentioned.

Thank you Jason. I checked all that stuff. It´s all chinese to me haha, but I set it like you said. We´ll see what happens...