I am having a problem where it tells me my saved builds say they are empty and will not let me post to Facebook

Don't try to post them to Facebook. There is a better way.

Save the build and at the bottom you get a shareable link. Highlight that link and copy it. If you are using a PC, just press <ctrl> C.

Keep a document open where you save your build links. Each build saved gets it's own unique link. When you want to post your build in Facebook, just copy and paste that link in your facebook message.

What i do for sharing builds is use the photo system. I get the gun oriented with the background I want then I take a 'snapshot', That opens in the picture viewer of your Windows system (or even Linux). Right click on the picture and you get an option to save it and give it a file name.

I give my builds a name and save their links in a simple text file with the name. I can call up every build I have ever saved that way.

If you have specific questions, feel free to ask them and i will do my best to help.

What I do is post the pictures in Facebook, not the links to the builds. I think about it this way, "as the designer, should I give all my secrets away?" :)