RStudio 1.4.1103
R version 4.0.3 (2020-10-10)
macOS 11.1 (20C69)
This is a recurrent issue. From an Rmarkdown file shown inside the main RStudio window, if you click on Show in New Window
for a plot, the new window shows the plot fine.
But if you first do Show in New Window
with the whole Rmarkdown file, and then click on Show in New Window
for the specific plot within the Rmarkdown file, the new window is empty.