It is not longer working the way it was with the latest RStudio release.
The behavior I get is that, after selecting the lines I want to edit, I see the multiple cursors, but when typing, the 'File' tab in RStudio pops/opens out.
Was something changed in the way we should use it?
Shift + Alt is a shortcut in Win11 to change the keyboard language distribution. So everytime I'm using the Multiple Cursors in my RStudio session I also change the language distribution of my keyboard.