Plane reflection when I press the G key or play the scene when the reflection effect will disappear,

Plane reflection when I press the G key or play the scene when the reflection effect will disappear, what is the reason

what you are seeing is the preview plane, that’s not going to show up in game, it’s just there to show you what the reflections look like. there is a check box to turn it on and off in the options of the planar reflections actor.