Hello,
This is because of the aspect ratio.
When you are in the editor, you see the game area in full edit mode, and when you run the game it runs in 16:9 mode, and it causes your asset to disappear.
We will add an option to edit the game in 16:9 mode and it will solve the problem.
Until then, try to change the editor window to suit the game aspect ratio.
Regards,
Cyberix3D team