Upgrade from 2014 CTP2 to Developer 2014

I am trying to upgrade an expired version of SQL 2014 CTP2 12.0.1524.0 to SQL 2014 RTM.

I run the Edition upgrade wizard and select the Instance I want to upgrade but the summary screen only displays SQL Browser and SQL Writer as available to upgrade. The SQLEngine remains on the evaluation version.

Any ideas on why the SQLEngine remains on the evaluation version and won't upgrade to the full developer edition?