Outstanding! Thank you. I was noticing how I'm having to retrain myself to make this shortcut a first-class tool now that it's working reliably. I didn't realize how much I'd conditioned myself to avoid it. It's nice having this workflow back.
Just wanted to note that today I found myself using both directions of the shortcut between terminal windows and was genuinely delighted to be reminded that it's working properly again after a decade and a half!
I found that Sash forward switching works about 97% of the time, but still occasionally has a hiccup. Have not been able to pinpoint a cause yet, but I find that even in that case the reverse shortcut still works.
Even without that, I find myself using the reverse shortcut more than I thought I would, so that was a good suggestion.