Facebook tabs don’t work on a mobile. This is a known issue, but by adding some parameters to the URL you can force the Facebook iframe tab to load as though it’s in desktop mode.
The simple reason for this is facebook redirects people to m.facebook.
In other words what used to be:
Tries to render as:
https://m.facebook.com/yourpage/app_3242342342 which will give you a page 404 error.
There is a simple fix:
If you have control over the domain URL, you can change it to include the following:
Hope this helps someone.