Unfortunately, this was never intentional behavior -- the label in a choice is not supposed to be dynamic and this structure worked accidentally. The fix that caused it is for index-repeat with relative expressions. I'll see whether it's possible to bring back the previous behavior but I'm not sure.
Generate multiple choice alternatives, based on the answers in a repeat - #4 by LN is the XForms way to do this. https://github.com/XLSForm/pyxform/issues/38 is an issue to bring this functionality into XLSForm.
Can you say more about what you mean by another support team? If you see changes it behavior in ODK tools, it's helpful if you can bring those to ODK developers so we know about them.