Hello -
The Reflections settings are governed by the reflection actor in the level and for a hallway scene like you have I would suggest using a Box reflector as opposed to a sphere reflector. It is important that in either case your bounds of the reflection include the extent of your area. All that being said, try those if you are still having an issue a video would be most helpful in narrowing down the exact cause.
Thank You
Eric Ketchum
EDIT: Also just to check do you have your indirect lighting built in your level as the reflections require that to render the cubemap? Also add a skylight to the level with very little intensity (unless you need it) and rebuild, does that help at all.