Upgraded to 5.1.5, Facebook login icon is missing

[Ttakala]

I just updated from 5.0.5 to 5.1.5 and everything appears to be working normal, EXCEPT the "Login or Sign Up" panel is missing the Log in with Facebook icon.

I still have the correct settings from this guide:

https://www.vbulletin.com/docs/html/facebook_enable

My host is Media Temple and for my forum I have enabled PHP 5.5.21.

Any ideas how to fix this?

[Zachery]

Do you have cURL with SSL available in PHP?
Is your facebook application properly configured?

[Ttakala]

Do you have cURL with SSL available in PHP?
Is your facebook application properly configured?

According to this I do have cURL with SSL enabled:

http://s81345.gridserver.com/gs-bin/phpinfo.php-latest

I haven't changed anything from Facebook app settings from the time that it was working. I checked from Facebook's App settings, and the App ID and Site URL seem to be correct. Are there some additional settings required by 5.1.5, that are not described in your "Enabling Facebook" guide?
When I click the "Sign Up" or "Register" link in my forum, the "Connect with Facebook" icon appears above the register form fields and it appears to be working, but for whatever reason the "Login or Sign Up" panel is missing the Facebook icon.

Oh, I checked this both with Chrome and IExplorer, and it shouldn't be a AdBlock or some other script blocker issue.

[Zachery]

Are you using the default style?

[Ttakala]

Yes, I'm using the default style.
I just tried it at my work with a different computer, and there the Log in with Facebook icon appears normally. I'm not sure what is different. I'll try with another computer tomorrow. You can also see if it works for you:
<link retracted>

[Zachery]

I see the facebook button just fine. Do you have any adblockers or other things that might be filtering requests from vacebook?

[Ttakala]

Thanks for checking it. I've now tested the forum with 4 different computers. The only one where the Facebook button is not shown is my home computer (Chrome & IExplorer).
In Chrome I only have DoNotTrackMe but disabling it doesn't help. In IExplorer I don't have any adblockers and JavaScript is enabled. In incognito-mode the Facebook button works on both browsers.
Anyway, it seems that this issue only affects my computer or a minority of users. It still would be good to know what causes this.

[Ttakala]

Update: I tried again today, and now the Facebook button shows correctly also on my computer (both Chrome and IE).
I did not change anything. If I had to take stab in the dark, I'd say that maybe some cookies on my computer expired and got renewed, or something.

[AlexTheRota]

I am having this issue. On page load, the button is missing (styles look a little broken around that area too) in the login or signup box. If I navigate to another page this way, then open the login or sign up button it is there, and functional. Returning to the home page the button is still present and functional. It seems to be the initial load in where it breaks, at least for me on VB 5.1.8 (forum.nexonm.com)