If ~/Library/Logs/Extensis/ folder is inaccessible, Suitcase Fusion is not able to add fonts to the font library. It will create a set for a matching folder name, but the fonts never appear. Suitcase Fusion and Universal Type Client will not generate an error or warning message.
This will occur on all compatible versions of Suitcase Fusion for macOS.
Fix the ownership and permissions on the ~/Library/Logs/Extensis/ folder. If you are unable to perform this process, please contact Apple or Extensis Support for more assistance.