Thanks for including your files to help with this.
What you’re seeing is expected Shift + Enter is not recognized or needed as a way to setup single space line break. Mac and Win should both recognize “only Enter” for single line break. You can use “Line Spacing” control in Property Inspector if you’d like different spacing.
Is there something you’re specifically looking for that you’re unable to do by selecting “only Enter”?
Adobe XDAlex commented
Any movement on this in the last 6 months.
Kind of annoying that sharing files with people on Macs causes all line breaks... to break.
We also see the reverse of this - where some (??) text lines created mac just appear with the "box" unknown character when opened in windows.
e.g. saved on a mac:
"This is a test line
with a line break"
"This is a test linewith a line break".
Obviously not user error - if I share a document to edit it should show up looking the same at the destination :( :( :(