IF YOU HAVE DOWNLOADED THE 4.5 UPDATE, PLEASE RE-DOWNLOAD IT IT. THE OLD VERSION ENDED UP BREAKING THE GAME!!!
The new file is called mod1.zip.
If it is not called this, then that means that the file has not yet been approved and you need to check again later.
I stupidly uploaded the wrong file which ended up taking all the meshes we imported and made them invisible. please re-download it and it should all be working now. please leave bug reports in the comments!