Play videos < iPhone X

Hello Unreal Engine Community,

I have a very strange problem. Namely I have a video file mp4 / h264. Playing it works on iPhone +X as well as on Android everything without problems. However, I pack the game on an older iPhone. In my case, the iPhone 7 Plus. The video remains black. Do you have any idea why on older iPhones the video stays black? Resolution of the video is: 828 × 1792. is there a limitation of the resolution?

UPDATE: Video size changed to 750 × 1334 and still black.

Kind regards

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