I loaded it onto the code.appinventor.mit.edu server, and tried a build.
Even while loading, I sensed by the timing this is a big project.
You have almost two dozen screens.
That's over the normal limit.
You also have lots of Media files.
I deleted the .odf Media file, expecting it to be useless for AI2.
Here is the first screen with empty sockets:
(I stopped looking after this.)
Try to build again after each screen is spotless.
If that doesn't work, see