I too am having the exact same problem. After migrating to 2.5, I attempted to install a different GavickPro template (gk_musiccity_J!2.5). I installed it through the extension manager just like I did millions of times before with Joomla 1.5. The extension manager says the installation was a success. I can see the folder via FTP, but the template is nowhere to be found when I go to my Joomla 2.5 template manager. I too only uploaded the template.
This is a pretty big problem here. Moderator, twice now you answered princer's question wrong. Princer, like me, is not using QuickStart so please quit referring us to the QuickStart wiki page. Why are Gavick Pro 2.5 templates not showing up in Joomla's 2.5 template manager after a successful upload.?