Hello @pathology , from what I can see the code simply doesn’t load. Seeing as it works on my site.
Could you check the following things?
1. If you have a cache plug-in enabled, please clear the cache.
2. Did you enter all the requested information in the plug-in settings menu?
Alternatively, as you have a facebook business page, you could try add it manually, when you head to the business manager -> Inbox -> Chat plug-in -> settings and configure it from there. Eventually you will get a bit of code which you’d have to pase in your web page. I’d recommend adding it to your footer, just so it gets added on all your pages.
After you’ve done this, refresh your browser and open the souce code. Simply press Ctrl+F or CMD+F (depends if you use windows or apple), and search for “fb-root”. When you see this ID, the code has been succesfully added and you should be able to see the messenger box on your screen.
I hope this helps ??