Copy, cut, and paste keyboard shortcuts don't seem to be working in pop-out windows for script editing. Right clicking and manually selecting copy, cut, and paste work, but the keyboard shortcuts do not. Oddly, this works while the file is still within the main application (i.e. before popping out), and on the console. So this is isolated to pop out windows only, from what I've noticed.
This is using RStudio 1.3.776-2 Preview Build on Windows 10 as of 04FEB2020.
Also note that I re-downloaded and reinstalled RStudio completely and re-confirmed the issue.