As far as I know, the issues can be
1. Browser? (Try different browser and test it) Most common one.
2. There is no explicit settings for an extension unless you disable the default extension rule in 'Security Rule'
3. Maybe check the .js script for your extension button and if it has same common script as your other extensions for compatible devices, Browser Support etc...
But yeah, not pretty sure why that's happening. Maybe anyone else can help you?