Technical Single bolt airbox?

[Almiscarado]

Hi there,
Today I was trying to remove my airbox in order to clean the tb a bit, but juy couldnt undersdtand how to do it. It looks like it only has one bolt (on top), but after unbolting it, it does not want to loosen up. Am I doing something wrong, is there any hidden bolt or do I just need to pull it a bit harder?
Best

 

[purple haze]

Pull

 

[Bougainvillea Rosso]

Undo the clips at the side and the one underneath at the front too