Sometimes when I try to save, the "Uploading 123 KB..." notif just doesn't go away ever. If I click it leaves, but it never says that it saved. This just comes and goes regardless of the project. Why does this happen and how can I avoid it?
I think you just need to be a bit patient, as uploading a project of that size to the Snap! servers might take a while since the system isn't exactly perfect. 
If that happens you should save the project to your computer (export) so that you can make sure your project is safe.
It happened to me too, it wouldn’t go away even though I waited for 20 mins, it worked when I saved the project again.
Weird, but I don't know much about Snap!'s cloud system.
I wonder if BH or Jens have an answer.
You mean, you wonder if Bernat or Michael has an answer. Not me, and probably not Jens either.
Oh. Then in that case, yeah.