In RStudio, File -> New File -> (any option) opens a window, but the window is grey and I can't type in it. Restarting my computer and reinstalling RStudio did not change this.
Note that R, and all other aspects of RStudio, seem to function fine.
It worked correctly previously - I last used it perhaps two months ago.
I don't think I updated it between the last time I used it successfully and now, but I could be wrong. I definitely updated the OS and other things in that time.