End portal not spawning in stronghold

Hi there, i would like to address this issue i came across twice already. Upon entering the stronghold, only the library and a few rooms spawned in, but the portal did not. On the first world, the stronghold spawned near a mineshaft and my thought was that the mineshaft prevented the portal from spawning, but as you can see from the pictures (i used a boat clip bug to see trough walls) this time there's no reason for the portal to be obscured by any mineshafts or other natural structures. Unfortunately i deleted the first world, but i felt like adressing this one. Is this normal or am i just having bad luck?