I know I posted this eariler today, but I have a bit more information.
Since I can perform 'mvn deploy' from the command line, I disabled the 'Deploy artifacts to Maven repository' post-build option and just used the following in my Maven "Goals and options":
clean install deploy
It worked!
Then re-enabled the 'Deploy artifacts to Maven repository' option and reverted my 'Goals and options' to just "clean install"
I then used wireshark and was able to verify that the 'Deploy artifacts to Maven repository' option is sending the correct user name/password (Basic-auth) and thus it is reading the correct settings.xml.
What is so different between the 'mvn deploy' and 'Deploy artifacts to Maven repository' post-build action?
How can I enable more debug output for the 'Deploy artifacts to Maven repository' post-build action?