Unwanted Matriarch Filter/ VCA drift

[Koude]

I experience an unwanted LFOesque drift in the VCA / Filter behaviour, even when all attenuators and modulations sources are disabled / set to zero.

I play an 3-note arpeggio on hold. The timbre/colour of that arpeggio should not change.

But the colour (rather amplitude?!) of the notes does shift over time. Every 10 seconds the first not of the arpeggio has a low volume / or slow attack.
The frequency of the drift does not seem to be affected by any LFO / Modsource, or rate of the arpeggio.

No patchcables used. Clocked with midi.

Any ideas what is going on here?

Thanks!

[Magpel]

Just out of curiosity, does the issue still appear when you are playing a single oscillator?