Related UDNs:
https://answers.unrealengine.com/questions/597988/vertex-snapping-static-meshes-to-one-another.html (2017)
[Link Removed] (2015)
Snapping an object's pivot to a vertex location as described here: https://docs.unrealengine.com/en-US/Engine/Actors/Transform/index.html#vertexsnapping no longer works
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-82526 in the post.