Neither Guardians nor Pillagers Spawn

Updated 1.17.1 world to 1.18 Pre-release one. It is on a server if that matters. 6 Gigabytes of ram, entirely vanilla. 

Guardians do not spawn in preexisting ocean monuments, but they do spawn in newly generated ocean monuments. The same is true for pillagers. They will only spawn in outposts that have been generated in 1.18.