Do you still see the same problem if you try a fresh user account, or move the Featherpad settings out of your home folder to reset them? If so, the developer is quite responsive if you open an issue about that on his github page.
There are some more features coming up, such as today's that let you open a URL with a click, but I'm going to let things shake out some more first:
I willingly contradicted myself because this was so cool:
(1) Added this feature for all syntaxes that supported URL formatting.
(2) Increased the version number to 0.8 because there were several big changes since 0.7.
To detect or click a hyperlink with mouse, Ctrl should be first pressed and hold (the cursor will change to a hand on hyperlinks). That's intentional because otherwise, it could interfere with text editing and might take the CPU time.
Hyperlinks can be local or remote; there's no limit to them. They will be opened by appropriate apps, as far as the system knows how to open them. perl-file-mimeinfo (libfile-mimeinfo-perl in Debian) may be needed for that.
I'll add this info to Help later.
This might need some polishing later but I hope it's free of bugs.