certain sections in one object preventing another object from appearing in-game

in this blend file, there are 2 objects … a cylinder at the bottom, and an object at the top comprising of a colour scrolling curved part and a long rectangle with a wood looking texture

if you press p to start the game engine, the cylinder disappears

edit the top object , delete the rectangle , then start the game… the cylinder still doesnt appear in game
undo your action, so the top object is whole again…
edit the top object again, but this time delete the colour scrolling curved part… the cylinder now appears in game

why?

Attachments

alsonotappearing.blend (598 KB)

There is an unamed material in the pink object and im not sure why, but removing it or pressing new fixes this problem.