Mecanim Sprite Animations - Playback Differs on Different Platforms

I'm using mecanim to do a simple fade-in / fade-out of a sprite. When playing in the Editor, the animation looks great. If I build to PC or Mac, the animation also plays well. However, if I build to Web, the animation state gets skipped. It goes from start to end state ignoring the fade. To make matters even stranger, this only seems to happen when I build from my Mac. If I build from a PC, the animation plays normally on the web. Additionally, none of the character animations that are set up using mecanim are having this problem, only the sprites.

I would just build from the pc, but unfortunately my build machine is the Mac and the PC version exhibits other bugs that the Mac version doesn't (skin errors, another issue entirely). I'm not sure what's going on but it seems the later releases of 4.6 seem to have some differences depending on the development platform. I've verified the quality settings for web vs. standalone and even taken the build settings from the PC in version control just to be sure. I'm not sure where to go from here to further investigate this problem.