Xjadeo only shows even-numbered frames

Noob alert. Prepare yourself before reading on:

When I move the playhead around to view video, the timecode box only advances on even numbers, which in turn only advances Xjadeo on even numbers. The only way I can get odd numbered frames to display is when I pause playback at the right time. Is this expected behavior? Or something I can change? Or did I mess up a setting somewhere?

I’m in 5.10 if that helps. Happy to provide any other information required.

Maybe grid settings in Ardour?
…or an incorrectly configured timecode ? Session > Properties > Timecode/Sync

If disable the grid, then I can get it to work properly, but I really like the grid. So, with grid set to Magnetic and the Grid Units set to CD Frames, it works, but that eliminates the point of using the grid, because it’s still harder to line up audio directly on a frame-by-frame basis.
If I disable Adjust Session Framerate to Match Video Framerate upon selecting Open Video, then seeking through the video on a frame-by-frame basis works as it should. However, is this going to cause problems when I want to apply the audio to the video when I’m done mixing?

What framerate is the video?

The framerate is 24 FPS.

When you play the same video in xjadeo without ardour, do you have same problem?

I had a problem with that, the sound was ok, but images were extremely slow. The problem was in the graphic card.