I've never waited inside a castle or town and the only time my king pretended I didn't ask for a fief was when I capture a town and asked for it then captured another fief and claimed too. The king pretended I didn't ask for the town and gave me the second fief. Since then I only siege a fief after receiving another one

The king of the faction gives them to the other vassals of the faction. Until you become a king yourself, this can not be avoided.

I can't find confirmation on whether this is a bug, and whether there's a way to fix this.

I capture castles/towns on my own, I request them, I have been inside them sometimes when they are awarded to another vassal of the faction I'm a part of. I haven't seen the option in a while. 

Does it have to do with right to rule or lord relationships or something?

Stopped getting option to rebel