Porting saved world into 1.14 stopped Hostile mobs spawning naturally

Made a world in 1.13 and then ported it into the newest update. Pretty much everything worked as normal, new villages and structures were spawning as normal. Except that no hostile mobs were spawning. Tried changing change rules but made no difference, and was playing in hard mode. Pillagers do spawn if omen buff was given through commands and then went into a village.