When Luke is hiding from Vader under the throne dais, the consoles he’s using to conceal himself don’t even reach to the ground. When he screams “No!” he’s right out in the open like Vader couldn’t see him. there needs to be more of a maze of consoles and equipment underneath the throne.
Totally agree, that he should not be seen that easily. But I was always thinking that he is using some kind of Jedi invisibility trick, or whatever, so Vader can’t see him. (I convince myself with BS too. From time to time.)