When you get a fix it email it can be one of two reasons. 1) they have reviewed your app and noticed your missing a few items needed in order to get an intervew or 2) your app was screened and error was noticed so you get an email to fix it. If your scenario 1, then your one of the lucky ones but if your scenario 2, then you could be waiting quite some time until your application score reaches what they are looking for. You will not have any clue which of the two scenarios you fall into so that's why some get an invite right after they fix it and other have never heard a word since.

Once your app is looked at by one of the 4 screeners they will give it a score which then places it into one of 4 tiers for hiring. Updates or changes and job fairs will get your app pulled and looked at again but rarely does your score change. I was told once it's placed into a tier it will stay in that tier. You can move to the top of the tier with changes but ultimately once it's given a score it's not going to change.

I was given this information from one of the screeners as well as a guy that does the interviews.