I have two Sony HDR-AS15 action cameras I have used for stereoscopic filming. I have previously successfully paired several clips from them into stereoscopic subclip, and it has worked just fine.

Yesterday, Vegas suddenly refused to pair two new clips. Just as before, I placed the two clips on two tracks in the timeline, right click -> Pair as a Stereoscopic 3D Subclip -> nothing happens - the clips remain unpaired. (but strangely, the Use Count of the clips increases in the media pool view)

All new test clip pairs I have recorded after yesterday afternoon, have refused to pair since.

All the clips I have recorded before yesterday afternoon, can still be paired just as before. Here's the proof Ive already done it before:
http://archive.org/details/JulianLaynPianoStockholm20130713

- The settings between the cameras are identical. All videos are 1080p, 60 fps from both cameras. These specs look the same in Vegas media pool as well
- Both cameras have the same firmware version
- The video files can be viewed on any player, and display normally in Vegas Movie Studio
- ..... the only thing is, that the clips recorded after yesterday afternoon refuse to pair as a stereo 3D subclip. (?!)

I'm dumbfounded. What could possibly have changed, or gone wrong?

I have already attempted to reset the cameras, and format the memory cards. The video files don't appear broken in any way, but I may need some video analyzer software to see if something is still broken somewhere.

I have tried the pairing both in Vegas 11 and a trial version of Vegas12 (x64). Same problem on both.

I can provide a pair of clips that can be paired, and ones that cannot be paired, if you Vegas developers want to take a look at them.