Still feels a newbie with blender, so I have also dummy question. But while looking for the solutions, it looks that I'm not the only one. I'm trying to follow Ray Mairlot's You tube: Blender Tutorial: Laser Cutting Text Effect.
At 4:30 he adds the "Stretch to" constraint, and hit the same problem than many others. The object turn to away from the source object. See my simplified example:
Like on the other solutions, he rotate the object to -90 and bang! it is in correct position.
The answer I'm looking for is, what is actually causing this? Why rotation of the object should fix a problem? I mean, what is the error in a first place we all made to cause this?
And yes, I did not manage to get this fixed :D No matter how much I rotate it, it never follow the object. Some proposed to use "Copy rotation" constraint as well, but that was not helpful.