I have a dashboard that worked fine on 4.2 but no longer renders properly on 4.3. It has multiple flashtimeline panels and only the first one will render the timeline. This appears to be a flash/browser issue as it works on IE but not firefox/chrome/safari.
Broken in version 5.0x and 6.0.x as well. Haven't tried 6.1.*
I also ran into the same problem on Mac with Chrome and Firefox. Only the first FlashTimeline module will get displayed in a view.
Have you got the latest flash player? I had a similar problem which was solved with a quick upgrade.
Didn't work on any browser until I updated flash in Windows. Now works on IE but not others. Doesn't work on any browser on Mac.