Thanks Peter.
UPDATE: Fixed by accident or, could be part of a recent update… I’m not sure but it now works well 😀
One thing I did do differently (which is why I think it may have been the way I originally connected the system)
Originally, I had set up the Lab 28’s as a stereo pair and then added them to the Theatre using Wireless Power Link. I think this was just a pass through of signal/sound to the 28’s (via Theatre). Worked ok.
Recently, I reset the whole system (mainly because I was bored 🥱) and added the Lab 28’s individually as L & R speakers using Digital Power Link – bingo. Now when I choose a source that is set to use just the Theatre, the curtains stay closed. Further, switching different sources will open and close the curtains as per the setup in the listening positions.
Disadvantage: I am no longer able to wirelessly stream or airplay to just the 28’s. Everything must go through the Theatre. I’m ok with this as it can be tweaked via the source to play just through the 28’s
Overall a good result and I’m here sharing my learnings not only because I am excited but to assist anyone with a similar issue.