So are you saying that at the moment Amira timecode can't be relied on even with a sync box, as it resets to system time at random? This would explain some problems I had recently, but I put it down to a mistake somewhere in the process.
This only happened when I synced the Amira to my 664's clock, but not the other way round (although this was only two days, so difficult to diagnose conclusively)
If the system clock has timecode level accuracy then that would give a workaround of jamming recorder to camera until a fix is issued, but only work with one camera.