I've noticed something like this a few times as well; like the dream is trying to conceal something, or to keep the dreamer from becoming too powerful. I have a couple of theories about this, but I feel like it may be a psychological limitation. If you believe there is going to be a rule to keep you from doing something, if you have doubts about your control, if you think doing a particular task will make you wake up, then the dream will likely make it so. This is also why things chasing you in your dreams almost always find you. It's constantly in your mind that your pursuer may catch up to you at any moment, so you can never get away.

It's kind of like the lucid dreaming trick of rubbing your hands together to "stabilize" the dream. There is really NO NEED of doing this other than its placebo effect. You never have to stabilize your non-lucids, after all. But rubbing your hands together indeed makes the dream more clear, because so many people have told us that it works and we believe that it will work. In the same way, if you get the intuition in a dream that there is some kind of dream rule you need to follow, the rule will hold true because of your belief in it. Sadly, it's not very easy to just *stop* believing in something.

I think that maybe the way to overcome this is to believe in something that overshadows the original belief. This could be any number of things, like a magical amulet that protects you from any "rules" the dream creates. As long as you actually believe it will work, it should short-circuit the rule.