I suspect that there might have been an update to Electron that caused this. For now, I've disabled sandboxing. In order to have RStudio launch without sandboxing from the command line, I added the following line to .bashrc :
export RSTUDIO_CHROMIUM_ARGUMENTS="--no-sandbox"
In order to launch RStudio without sandboxing from desktop environments, filemanagers, etc, I had to edit /usr/share/applications/rstudio.desktop. I changed the line:
Exec=/usr/bin/rstudio-bin %f
to
Exec=bash -c "/usr/bin/rstudio-bin %f --no-sandbox"
Of course, I'll have to give @dickoah's solution a try since disabling sandboxing doesn't sound like a smart thing to do.