Attaching a Skeletal Mesh by setting it's Parent Socket causes the mesh to be offset and rotated
I still need to test using the BP you recommended. I tried again using the character blueprint - components tab in the ShowDown demo, making the camera a child of the player, and attaching to the head socket, and I got the same wonky effect (the same effect is given if you try to attach the head to the mesh in the same fashion). Or any other mesh for that matter. I'm attaching pictured of the steps to duplicate the issue.
1. Open QA-game
2. Open the 'BP_QAPawn' blueprint
3. In the Components tab, add a SkeletalMesh component
4. Drag it onto the Mesh component as a child
5. Set the Mesh > SkeletalMesh > Set it to 'SK_Mannequin'
6. Under Sockets > ParentSocket > Set it to 'head'
Results: The SkeletalMesh will offset and rotate 90 degrees
Expected: For the SkeletalMesh to keep it's relative location to the head socket
Head over to the existing Questions & Answers thread and let us know what's up.