Creepers, Skeletons, Zombies are absent from Windows 10 Bedrock Beta

Please Note: The Affects Version/s Drop Box above does not accept my current Beta version 1.2,13.12 which is the version I am reporting.

Spiders, cave spiders, the drowned zombie, and infrequently witches are the only hostile mobs spawning in the Coastal Village Seed, -1813740965. I am playing Survival / Difficulty Normal. Versions 1.2.13.10 and 1.2.13.11 had a few of the named absent hostile mobs spawn. I tried re-creating the world, but creepers, skeletons, and zombies were still absent.

Update 2018/03/25
I changed to Hard Difficulty. After a long game session, the world spawned the following. 3 creepers; 1 zombie; 1 zombie villager; many drowned; a lot of spiders; and a witch; but no skeletons.