Thanks, all. I figured out the perfect solution! Here goes:
The key to the puzzle is MUTING (left-click) the tracks you don’t need, rather than soloing (right-click) the one you do. That way any other tracks that influence the one for which you are creating a stem (eg. a kick drum that controls the Signal Follower effect on a relevant subgroup) are still working their magic, albeit silently. When you use the solo function, this behaviour does not occur.
I just created a perfect set of stems that, when summed in a DAW, sound EXACTLY the same as the master output render. For example the bass guitar stem on its own has been affected by the sidechain kick exactly as it would have been during the full mix, and the ducking effect is audible when I play it back on its own after rendering. Creating a stem by soloing the bass track would not have achieved this.
It’s a little fiddly where groups and subgroups are involved, so I thought I’d include some examples below (the required stem is the track marked in red each time):
In this one, I needed a stem of just the bass guitar. I had to mute the Drums group, the ungrouped track called Clappy and the Non-[basses] subgroup on the right, as well as Synth[Bass] ie the other track in the Basses subgroup. Also sends S01 and S02. Essentially mute the highest level of group that doesn’t include the stem you want, mute the non- required ungrouped channels, and mute any other tracks in the group containing the stem you require, as well as unused sends for that stem. (Phew!)
In this example, I needed to create a stem of Hats, the hihat pattern. I muted all the non-Drums groups at their highest level, as well as Clappy (the only ungrouped track), and the send returns S01 and S02. Within the Drums group I muted each non-Hats track.
For this one, I needed a stem of Strings, which has a send return on track S02. It’s the same principle as before, ie mute the Drums group, mute Clappy, mute the Basses subgroup, mute everything else in the Non-[Basses] subgroup (Hypnot…, Piano, Chord, Wurly, etc) and mute S01.
At the end of this somewhat laborious but entirely logical (and potentially programmable - @dltfm?) process, I had the most perfect set of stems I have ever created on a DAW. The eureka moment was grasping the difference between muting unwanted tracks and soloing the required one. Hopefully this helps others!
(Edit: I should mention I am on Windows, in case the above doesn’t work on Mac/Linux, though I don’t see why it wouldn’t.)