Firefox 188.8.131.52 on Vista; in the FoxyProxy options window, if I try and add a new proxy, at the end it does not appear in the list of proxies. When I close the options window, I get two messages: "AutoAdd: A pattern is required" and "QuickAdd: A pattern is required". After closing & restarting Firefox, whatever proxy I entered has vanished (previously was selectable in drop-down lists). The status bar icon is also persistently missing. It doesn't matter what other extensions I disable - I was running the same set of extensions (same profile, actually) in Windows 2000 and it worked fine.
Sounds like you used some profile backup tool to move FoxyProxy to another machine. Is that correct? Those things don't typically work with FoxyProxy. But it's ok-- all you need is foxyproxy.xml. Copy it to the new installation and it will overwrite FoxyProxy's default settings.
I've tried un-installing & reinstalling FoxyProxy - are there any other settings I should be aware of as to why it's not displaying correctly?
I just found what the problem was for me!
For some reason Global Settings -> Settings Storage Location field was empty. Once I changed it to point to foxyproxy.xml in my profile - everything went back to normal.
On my Vista foxyproxy.xml was in this folder: c:\Users\<username>\AppData\Roaming\Mozilla\Firefox\Profiles\<profileid>.default\foxyproxy.xml)
Hopefully this will help to others as well.