In the new Premiere Pro version 15.0, the order of the stream is reversed for H.264 / MP4 exports. Originally from Stream # 0:0 = Video, Stream # 0:1 = Audio In the new version, this has been reversed Stream # 0.0 -> Audio, Stream # 0.1 -> Video, so a few servers and software will not accept it. It would be good to remedy this as soon as possible.
Or maybe someone has some idea where the mistake might be ??? Thanks!!