I'm completely stumped by this. One of our designers asked me to try animating a design of his into a web banner. It's my first time doing anything like that, so I assumed there would be some troubleshooting, but this is just getting weird.
There are a ton of things weirding me out, so I'll try to summarize. At one point I had it working to where I could export a SWF of what I had animated so far. The file size was larger than we wanted though, so I decided to try removing one of the moving elements to see if that would decrease it. When I removed it, the SWF would no longer export properly. It would create an empty file only 22 bytes large. I couldn't even just turn off the visibility - my animation would literally only export if this file was present and turned on. Weird thing is, if I moved it to the bottom below my background, where it was no longer showing up in my comp view... it would export! But I couldn't remove it from the comp. I tried removing other layers, and everything still exported just fine.
Fast-forward a bit. This thing has frustrated me to no end, so I've completely rebuilt the animation using only native AE content (Texts, masked solids) and .EPS versions of some photographs that had been present in the original. After some hassles with a few things here and there, I again got it working to where I could export everything. Then, again, I wanted to try turning off one of the moving elements to see if it affected file size. In my previous example I described, this had been an .AI file. I'd since converted it to a masked solid. And again, when I removed it from the comp... somehow the entire thing broke and would no longer export a valid SWF file!
I've tried dozens and dozens of tests to try and nail down exactly what's happening and what I need to do to solve it. I'm stumped. I've tried changing file types, removing certain effects from the comp, animating in different ways... can anyone explain what I need to do to make After Effects export SWF files consistently?
I know it's a long shot asking something so vague and complex.
That works if all I need is to get the file into .SWF format, but defeats the purpose of creating a .SWF in the first place since the file size ends up being enormous. I'm working on a 12-second animation that needs to be cut down to under 200K in the final deliverable, and that can only happen if all of the vector art stays vector.
I ended up having success with saving the project as a CS5.5 file and opening it in that version, which apparently doesn't suffer from the same bug that CS6 does. It's annoying, but it works.
Looks like it's due to the CS6 bug you mentioned. I back-saved the file to CS5.5, opened it up, and exported with zero problems at all. Redid all my tests just to make sure, and nothing tripped it up! Seems like a pretty glaring error; I googled around a bit and found a thread with people talking about it way back in August when Adobe had already acknowledged the bug and were supposedly working on a fix. I'm fine just using 5.5 for this particular project, but that's only because I have both versions. The average user just working off of CS6 would be completely out of luck.