There are several ways to solve this, read thoroughly 🤓
First, try to close the extension and reopen it (in the Window > Extensions menu).
Also make sure that you run a supported version of Illustrator or Photoshop:
CC 2017 to 2024 & more are supported
Illustrator CC 2015.3 (version 20.0.0) or more recent
Photoshop CC 2015.5 (version 17.0.0) or more recent
If you are not sure, check the exact version number in the About Illustrator... and About Photoshop.. menus..
1. Download and install the latest version of Fontself Maker
Learn what's new in Fontself for Illustrator & Photoshop
2. Whitelist in your VPN
If you run a VPN (Virtual Private Network) on your computer:
First try to allow local connections in your VPN settings. Then restart Illustrator/Photoshop.
If it's still not working, disable your VPN and restart again.
3. Whitelist in your filtered networks / firewalls 🕸
All ports from 4766 up to 4886 (included):
127.0.0.1 (for this local IP address only)
Port 443 (HTTPS) for all urls below:
api.fontself.com
To make sure this URL works fine, just open this link in your browser and it should display a smiling emoji: 😏api.segment.io
cdn.segment.com
*.intercom.io
*.intercomcdn.com
api.amplitude.com
*.cloudfront.net
*.sentry.io
ssl.google-analytics.com
www-google-analytics.l.google.com
If none of these work, try more options here: http://help.fontself.com/en/articles/923399-extension-panel-is-empty