Ok. Have worked out how to reproduce. (This is all in 10.5.20).
1.Open new project
2.Create audio track
3. Open volume automation track
4… Hit record.
5. Adjust volume between min and max - as expected automation curve follows as expected between min and max, bottom and top of lane.
6. Create VCA track for the audio track
7. With unity gain on VCA all good,
8. This is where it gets a little funky and hard to pin down…
9. Change the VCA gain up or down
10. Go back and re-record new automation on the Audio track.
11. Going between steps 9 -10 you will see that as you record the automation curve on the audio track looks normal.
12. When you stop the recording however - the automation curve and the effective volume curve (the combo of the audio track volume and the VCA gain) - and the lighter coloured audio track automation curve is rescaled.
I thought there was a consistent error in the rescale - but all I can say are the results are unpredictable.
However - you do often get an event curve that goes outside the top limit of the automation lane. And once there, the incorrect scaling seems to stay, no matter what you do with the VCA, or the re-recording of the audio channel automation.
May be wrong here - but I would expect that the automation event curve scale should be INDEPENDENT of the effective channel gain (combination of the VCA and the actual channel volume level). Eg it should represent the automation controller value rather than the actual gain. The result otherwise is an automation curve that doesn’t re-edit.
Lots of words to describe - but you can see it by trying the repro pretty easily…