I have synth on track 1 (Pigments 6) and BFD 3 on track 2. The drums don’t come in until the start of measure 4, but the synth track is playing the drums also. It doesn’t happen with BFD Player, so it’s not a routing issue.
Double check the routing MIDI channels.
I found it, there’s a “Grv. off” button that needs to be toggled. The other track wasn’t triggering it, it was apparently just set to always play the selected groove when the track plays. I’m new to BFD 3, so that didn’t occur to me.