I have recently found a strange behaviour in Blender: sometimes when I delete certain objects in the scene, the JSON exporter becomes unavailable. For example in my actual scene, if I delete a specific plane it becomes unavailable, but not for any other meshes. Impossible to delete that plane.
However I can delete it with certain other specific objects, at the same time, and the exporter becomes available again. This as well only works with certain objects. Also, when the JSON exporter becomes unavailable, the same always happens for Motion Capture (.pvh) and Stanford (.ply) format export options. I have studied parent and material relationships but I haven't been able to find any logic in that behaviour.
What am I doing wrong ?
(This is a copy from this SO question)