Hey, thanks so much for these suggestions.
After a lot of fiddling, it seems like the conflict is maybe the nesting, or rather having 2 'Vertical Layout Group' components on 2 different nested objects. If I disable one of the Vertical Layout Groups, I don't get the issue. I tried replacing one with a Horizontal Layout Group, but no luck.
I did try a Layout Element - it gets rid of the recording position glitch, but I couldn't seem to get the wrapping of the text right (the text ran off the screen), or the background box just didn't shrink to conform to the text - this kind of double nested setup I have seems to be the only way I can find thus far to get the text to wrap correctly to a max shape.
I also tried your script, and just couldn't figure out how to get it to work with the Adventure Creator Subtitles menu I'm afraid - maybe the ACWiki script was clashing with it, not quite sure. If you have more suggestions for how to set that up correctly, I'd love to please try! 🙏