When I attempt to open the Maven Profile selector I frequently get an error similar to:

Unable to open the Maven Profile selection dialog
Could not resolve artifact org.lds.stack:stack-master:pom:3.2.4
Missing org.lds.stack:stack-master:pom:3.2.4

In this case stack-master is a parent pom my project has that is not in the workspace but is instead available from a repository in the pom.