I don't think any update would affect it unless the changes you made have been reverted. Go through the steps again and ensure it's all correct. There isn't much I can offer here, the guide itself is idiot-proof and should work. I haven't had any problems with it. I would recommend clearing your cache, refresh your page/browser and try again. Also, you can check things out and see how they should appear by using the sharing debugger tool. Use this one: https://developers.facebook.com/tools/debug/
Is there any way to modify this so that it actually pulls the image from the post you are sharing and not the first in the thread?
Reason I ask is that I have several threads of astrophotography captures, and typically the first image will be an original capture, and as time goes on and they gather more data for that capture, the images improve from stacking additional frames to them.
So frequently I'd prefer to share the better image out to my FB page.