unforch you can’t route multiple tracks into one buffer…
you can route them to CUE and resample that. or you could use MAIN and resample that. or you could use TR8 as MASTER and resample that.
plenty of options, and whilst your frustration is understandable, it will all become clear.
if it’s not working, take it apart and start again — don’t keep going and trying to track down an error, it’s easier to build from scratch and get it right that way.
…
also imo, there’s not a step-by-step from elektron because the functionality is open and implementable in so many ways that them giving you a prescribed ‘rinse and repeat’ format would kind of negate the beauty of what they’ve engineered. my $0.02