adding theme to Rstudio preview 1.2.1015 in windows 10 does nothing

themes

#1

adding any theme to Rstudio preview does nothing:

steps to reproduce the issue:

1- choose any theme from from https://tmtheme-editor.herokuapp.com/
2. Tools > Global options > appearance > add theme
3. choose tmTheme file and accept
4. Dialog blinks and "Textmate (default)" is selected. No new teme is available.