Ok, I’ve checked real quick and I think I need more coffee before I can figure this out. But briefly;
In a new clean project I created a few audio tracks. I recorded a small clip of audio. I automated a send for the duration of the event (meaning in/out markers/range to that event/selection, and then punch to loop). So the one thing I noticed then was that on other tracks I could place the send anywhere I wanted and when Read was enabled it wouldn’t matter, because no automation had been written. But once I dragged the event that had automation on it down to a track without, automation followed. If I then moved the event back to the original track it was on, the track that got automation because of the event still had automation.
So if you add that to what Fredo just said perhaps that will explain everything?