So, we sent tech support requests to Microsoft on this issue - twice. They ignored us for a long time, and finally responded basically saying that since no one else has reported this issue - they are not going to address it. Thanks!

The solution was to completely unistall Visual Studio (not just SSIS), and reinstall everything. My guess is that there was an another instance of Visual Studio (possibly installed by another user) that may have conflicted with the current install. The reason we think that is because on one of the un-install screens it said something like "Visual Studio (2)" - possibly indicating that there were 2 instance of VS on the computer. Just a guess. Once we cleared everything off and reinstalled - it worked.