shinyapp in Rstudio in ubuntu not showing correct fonts in ggplot

Inside app in ubuntu ( but not in shinyapps.io, and not outside shiny in Rstudio) ggplot not showing the chosen fonts. Related post: https://askubuntu.com/questions/1171970/how-to-render-fonts-in-ggplot-in-shiny-app-in-ubuntu.
Fonts are not shown in Rstudio or system browser. Problem exclusive of shiny apps.
Rstudio 1.2.1568