local players disappears when tool is equipped?

Hello! I'm currently making a roblox game with some of my friends. Everything works well, except for one thing: whenever we actually play the game to test it, my friends and I will see each other's character, and then become invisible to the other. We've noticed that that usually happens when we equip a gun. I don't understand why this happens. Any advice on how to fix this would be greatly appreciated.