Umg vedio works fine in editor but disappear after packaged out

I made an UMG video player ,the step is importing a video as a mediaplayer asset, and then create media texture and material .Then I create a UMG widget ,drag in an image components and assign the Media Material made before to it.Finally I created a variable and 3 buttons,The variable’s class is the MediaPlayer.and the 3 buttons control it by playing,pausing and stopping in Graph.
When finished ,I tested in Editor ,it worked fine .But after packaging it out , the UMG video disappera .So Why is it?

Hello fullorange,

This was a known issue (UE-28011) I have provided a link to the original post. This issue has been resolved and this solution can be found in the 4.11.2 release of the engine. I hope that this information helps.

Link: https://answers.unrealengine.com/questions/397532/menu-widget-not-visibleworking-in-standalone-mode.html

Make it a great day