To keep other people from having the same panic I just did :)

[desireearmfeldt]

I just posted to the DSSS_2014 collection, and discovered that (unlike my memory of last year), not only does my not-yet-approved-or-revealed submission not show up in my Works list, it also doesn't show up if I click the Works In Collections button.  HOWEVER, it DOES show up under My Assignments, where I can click on the file and continue editing as usual.

So, don't panic if you post to the collection and AO3 seems to eat your submission.  Check My Assignments to see if you can find it there.

(Caveat: I am not an official AO3 anything, just reporting my personal experience, here.)