After Casting Rising Colossus hiding fails always
If my gargoyle has casted risign colossus(RC) he fails every hiding attemp with the message "you are busy doing something else and cannot hide". There is a huge delay before he can use the hiding skill. If he casts after RC immediately another spell, for example heal, he can hide.
Even if the RC spell fails because a colossus is already there he cannot hide useing the skill.