Adobe Media Encoder appears to hang when opening the Export Settings dialog (Mac OS 10.10 only)
This issue appears to be related to older AMD cards, such as the Radeon HD 5770 or 6750M. It occurs in Mac OS X 10.10 (Yosemite).
At this time, Adobe does not have a workaround.
The issue only comes up on the first launch of the Export dialog box. After the initial launch, the dialog box appears at its usual speed until the system is restarted.