has URL that does not match with the URL of the page that’s making call to the Face Book App.
Hence you need to make sure that this field must always be set to the URL of the page that makes call to the Face Book App.
Have you actually just tried de-authorizing the application in the user's Facebook I'm sorry. Log into the Facebook profile of the user that you have set up as the channel owner.
This is not a Page / Group or the Application in the Developer area, but the personal profile of the user.
However, when I try to re-validate the Facebook channel by changing the user name to something else and saving and then changing back to the original user name, I don't get the validation prompt on the front end to confirm the user. Or is there a way I can get the validation prompt to appear.
When working with an access token, you may need to check what information is associated with it, such as its user or expiry.You may have limited success in displaying certain posts from a personal profile but most posts are not able to be displayed.If you’re using the profile to represent a business, organization, product, public figure or something else other than yourself, then we’d advise converting your profile to a page per Facebook’s recommendation: as there are many advantages to using pages over profiles.Some posts are filtered out by the plugin as they aren’t useful, such as ‘__ commented on their own status’, or if you are choosing to only show certain post types.If the post limit isn’t high enough then there may not be any relevant posts to display.