Bug with custom waveforms?

Hi there!

I have a brand new Super6 and experienced some strange behavior when switching DDS1 to the custom waveforms. It works as described in the manual at first: switch the knob of DDS1 or press the wave button and then all the patch knobs light up in a row and you choose one of the waveforms.
But when I mangle the sound for a while and later want to change the waveform again the super6 doesn’t react anymore to neither the knob nor the wave button.
Even when I changed to another patch choosing different waveforms also just won’t work anymore.

Am I overlooking something or is this a bug?

Thanks in advance!