No new mixer channel for added drum slot

I think my BFD 3.5 has gotten into a bad state. I can add a new slot to a kit and put a drum in it. It appears in the Tech tab and I can audition it by clicking on the drum in the Kit display. I can even see (and hear) it bleeding into the other channels. However, I cannot get the new drum (a second Floor Tom) to appear in the mixer - i.e., no new channel has been created for it. I’ve tried all the different ways of adding a slot, without any joy. I’ve tried the “add channel” button just above the mixer but it justs creates another slot - no channel.

Has anyone else experienced this?

Do you have the mixer fully expanded? Not sure about the latest version, but in 3.4 there is an arrow next to the +/- (add channel) which expands/collapses the mixer.

Thanks Fender_Bender.
Yes I have. The channel really isn’t there.
Phil