Hostile mobs spawning in fully lit room and hallway in Woodland Mansion

My sister and I have made a woodland mansion our base. There are zombies spawning creeper spawning skeleton spawning in a fully lit room and hallway, this is happening within three blocks away from the player continuously. This is a realm and we play mostly vanilla with a texture pack the only change to the game. No Mods and survival only. Hard mode. Tried to create a mob switch but that is not working either.