I have that option activate (MAC, Rstudio Version 1.1.383) and it's not working the way I need it to.
My wished usage is: Within a project, if I save my .R file with folds collapsed, close it, open it again, I want to see those those in the same state. That is not the case for me.
What works is : close project, open project, I find my folds in the same state I left them when I closed.
Why it's not enough: simply because I open and close .R files all the time within a session and this resets the folding every time.
Here's a shot of my state of preferences:
I'm sure I'm missing something, thank you for your help.