I've noticed this for a while that I can't complete the Apururu Unity RoE objective "Vanquish Crawlers (UC)" while fighting Felsic Eruca in Morimar Basalt Fields.

They look like crawlers to me! They yield experience and it's a non-Abyssea area. They count towards Vanquish Vermin, Vanquish Multiple Enemies, etc. but not for Vanquish Crawlers.