After upgrading to VS 2012, the .Net framework was upgraded in-place from 4 to 4.5 (4.0.30319.17929). Using the project properties to target .Net framework 4 does not appear to work as 1 developer was able to introduce a change that works on machines with the upgraded framework, but breaks the app for anyone running the previous .Net Framework 4. The target framework was 4 and not 4.5.
Uninstalling VS 2012 left the upgraded framework.
As a result, our team cannot use VS2012 until all users have been upgraded to 4.5 since the multi-targeting feature is not working.