I was facing a similar problem: Some fonts were loaded and rendered properly, but later, after some navigation, they started to render incorrectly (falling back to the system font). I checked all the fonts used, and the problem only occurred with fonts lacking 'name tables in the font.' Fontname: null Family Name: null Name For Humans: null The solution was to write that information into the font, and we haven't had any problems since. I used this script: https://github.com/chrissimpkins/fontname.py Execution (your experience may vary): python3 -m venv ./venv source ./venv/bin/activate python3 -m pip install fonttools python3 fontname.py 'My Font Name' './My Font Name.otf' Cleanup: deactivate rm -rf ./venv python3 -m pip uninstall fonttools