Object 'Fading' In When Set to Visible using TemporalAA

So I am having some rendering issues, I am sure they are basic but have not been able to find the solution through searches. I am new to UE4.

I have a spherical mesh using a reflective material that is hidden but I set to visible in code. When I do so, if using Temporal AA, The object ‘fades’ in very slightly over 2-3 seconds. I can clearly see the meshes behind it around the edges through the sphere, which in this case is probably 50-75% of the sphere.

There are also some weird artifacts involving the shadow of the sphere right around the edges of the mesh, so the closest part of the shadow to the object. It is really apparent for a half second that there is no shadow around the edge, even though the extending part of the shadow is fine. Then the missing part of the shadow fades in quickly, but is still apparent there is an artifact for 2-3 seconds before it cleans up.

After 2-3 seconds the scene looks great.

If using FXAA these problems do not occur, but the scene looks much worse, very jagged. All setting are EPIC. This is a very simple, low poly scene. Only a few thousand triangles.