tier 15 maps drop tier 14 waystones only

i used my best waystone drop chance waystones (15) including everything i might have been around 200%.
tried 2 times, both times i only got tier 14 waystones (5 combined).

2 more tier 15 maps with low waystone drop chance dropped tier 15 as usual.
will try again, once i get more high chance waystones.

May be something to keep an eye on.

update:
did another few normal maps (waystone drop chance <50%), got the normal t15 waystones.

was lucky and had another t15 135% waystone droprate stone and voila... t14 drop only.

If you're using the Corrupted Infusion atlas passive keystone, check the area level when you're inside of the map.