Ignore the fonts in your user font library folder. You should not be using those. Instead you should be using web formatted fonts stored on your computer. These should be Woff, Woff2 and TTF.
https://help.blocsapp.com/knowledge-base/font-manager/
If you are having problems with Google fonts I know they changed the link a while back and that caused some issues.
If this doesn’t work I would suggest filing a bug report.