Thank you very much for reporting the issue. As it turns out a CSS change in 1.25 caused this. This will be fixed in 1.26 release, but a temporary solution to the issue is, open wp-content/plugins/gantry/css/iphone-gantry.css file and change line 56 from:
#rt-menu , #rt-menu .rt-container {position:relative;z-index:10000;overflow: hidden;}
to:
#rt-menu , #rt-menu .rt-container {position:relative;z-index:10000;}
so we remove the overflow:hidden declaration. Flush the cache and it will work just fine. 
Again, thank you, and please let us know if there are other bugs.