Premiere Pro export black screen on mobile, just audio I exported a 9:16 video (vertical, for Instagram stories) from Premiere Pro 2018, encoded with H.264 and AAC audio, VBR 2 pass.

However, the video shows nothing but black screen on both my Samsung Note9 and iPhone 6, if I play it back in default players. If I use VLC on my Note9, it plays back just fine.

What is the issue of this and how can I fix it?

Many thanks!
Try using 4:2:0, which is the common subdivision in encoding for your use. If that doesn't work, I'm certain that samsung provided a list of codecs which work with their phone.