It seems like, in the automation envelope editor, Renoise will randomly choose ‘ticks’ versus ‘BPM’ and vice versa. Whilst editing ‘BPM’ on ‘Mixer and Transport’, it is either a value between 0-126 (‘ticks’?), or the actual BPM. It’s not clear how to get it to stay on BPM all the time.
When it is working in values from 0-126, it’s tougher to choose the desired BPM. ymmv