I can't see what I'm doing wrong.
I'm trying to bounce two mono tracks (80,81) down to a stereo mix. I have panning and levels set up the way I want.
I select the clips; choose "Bounce to Track", specify the destination track (81); and the source bus ("Monitor").

It appears to bounce ok but the rendered stereo clip that results is ignoring source track levels:

Tracks 80,81 are the source tracks, both directed to the "Monitor" buss.
I panned them first, then when I couldn't believe the results, I dropped the track gain down to -15 db and even cut out a section of the right-panned clip, just to see the results - and look at the result in Track 82! It's ignoring gain, possibly panning... apparently even a muted clip.
If anyone can spot what I'm doing wrong - I'd be very grateful.