.fb_iframe_widget_fluid {
    display: inline-block !important;
    margin-top: 10px !important;
}

(I'm sorry for my bad english :)

Please try this small CSS code. Put it in Dashboard > Forums > Settings > Styles > Custom CSS Code Textarea. Save it delete all caches, do Ctrl+F5 on forum front-end. Then test it on other mobile devices. Because mobile browsers have a hard cache, you'll not be able see the change immediately.

.fb_iframe_widget iframe {
     position: relative!important;
}

Also please don't use Private Session of mobile browsers. Facebook doesn't allow use Login Button on private sessions, it doesn't allow use Cookies so make sure you use regular (default) mode of mobile browser.

Excellent!!!

It worked for me.

Thank you.

Hello Robert,

Here is the Login below:

https://www.ballingaming.com/community/?wpforo=signin

Just trying to get the blue Facebook Button centered.

Thank you,

Connor

Hi Connor,

Please follow to this instruction, don't forget delete all caches and use private session of mobile browsers when you check it after each change, because mobile browser cache is very hard, you'll not be able s=to see the result: https://wpforo.com/community/how-to-and-troubleshooting-2/facebook-login-on-mobile-not-showing/#post-18807

Also put this CSS code to make it aligned to center on desktop/PC:

#wpforo #wpforo-wrap .fb_iframe_widget, #wpforo #wpforo-wrap .fb_iframe_widget span {
   width: auto;
}

Here is the Login below:

https://www.ballingaming.com/community/?wpforo=signin

Just trying to get the blue Facebook Button centered.

Thank you,

Connor

I had the same issue and it worked for me! 

What is the code to center the facebook button? It is on the left side on all my devices and computer browser.

Hi Connor,

Please leave your forum login page URL I'll try to help you.

What is the code to center the facebook button? It is on the left side on all my devices and computer browser.

thanks,

connor

IT WORKS PERFECTLY!

thanks a lot, 

.fb_iframe_widget iframe {
     position: relative!important;
}

Also please don't use Private Session of mobile browsers. Facebook doesn't allow use Login Button on private sessions, it doesn't allow use Cookies so make sure you use regular (default) mode of mobile browser.

The Facebook login button doesn't show up only on mobile! 

I see some conflicts using a VPN and AMP for WP plugin, but I am not able to deactivate AMP for WP otherwise I am getting 5xx errors! 

Did anyone find a solution?

I'm sorry but this is something we are not able to debug. You should disable plugins, change the theme to find the problem maker. make sure there is no other 3rd party Facebook API loaded in your website. Maybe you have FB SDK duplication.

Also I recommend create a fresh WP installation in subDirectory or in subFolder with default WP theme, only install wpForo and configure the API with new keys. Then test it.