Once a prerender has completed after effects takes a second to start the visual playback. VO starts straight away. This corrects itself once the timeline has completely played through and starts from the start.
This is a known bug. There are several threads on this forum.
As Rick says, this is a known bug with Mac OSX v10.10 (Yosemite).
After Effects with Mac OSX v10.10 (Yosemite)
Great - Thanks for that. Looking forward to a fix.
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