RStudio doesn't detect new fonts I install

[josecasasn]

I recently installed some new monospace fonts (e.g. Fira Code, JetBrains Mono) to my computer (Ubuntu) and when I go to global options in RStudio the new fonts don't appear for selection, even after a restart of RStudio and my computer.

[JackieMe]

same problem here: Fira Code fonts don't show up in settings in RStudio Linux version 1.3.959

I am using Cascadia Code PL now, it has ligtures too and works in RStudio.

[andodet]

Same here, attaching sessionInfo() output should it be of any help.

R version 4.0.2 (2020-06-22)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Linux Mint 20

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.9.0
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.9.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8     LC_MONETARY=it_IT.UTF-8   
 [6] LC_MESSAGES=en_US.UTF-8    LC_PAPER=it_IT.UTF-8       LC_NAME=C                  LC_ADDRESS=C               LC_TELEPHONE=C            
[11] LC_MEASUREMENT=it_IT.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
[1] compiler_4.0.2 tools_4.0.2

[pelafustan]

Same issue here. sessionInfo() output:

R version 4.0.2 (2020-06-22)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Arch Linux

Matrix products: default
BLAS:   /usr/lib/libblas.so.3.9.0
LAPACK: /usr/lib/liblapack.so.3.9.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
 [1] compiler_4.0.2  htmltools_0.5.0 tools_4.0.2     yaml_2.2.1      rmarkdown_2.3   knitr_1.29      xfun_0.16      
 [8] digest_0.6.25   rlang_0.4.7     evaluate_0.14  

Other user post a solution here, but not work for me.

[EDIT]: I found a solution that works for me.

In the folder ~/.config/RStudio there's a file called desktop.ini. Change the value of font.fixedWidth key and restart RStudio. In my case, font.fixedWidth=Fira Code.