I think there are a lot of people using Unreal and Blender. But there is a serious problem with the integration: some bones/joints are imported with wrong translations (the “unconnected” bones) when there are animations. (There is an old version of the exporter which works fine, but it has some limitations, like morph targets - it doesn’t export animations, so it can’t be used.)
I thought it was an issue on Blender, but I’m not sure anymore, because some people said the same assets worked fine on Unity.
My suggestion is: talk with the developers of Blender, because I think they don’t know how to procede.
There is an opened issue here: ⚓ T41719 UE4 - Blender FBX Export to Unreal Engine 4 Bone Translation Error.
The developer assigned to issue still thinks that it’s a bug on Unreal Engine.