Thank you for developing this encoder. Finally, I have time to try out your encoder.
I use 2-pass encoding with ABR set to 2500kbps. The output video plays fine in Windows with MPC-HC, but I cannot stream it using AirVideoHD (http://www.inmethod.com/airvideohd) nor copy it to iPhone (using FileExplorer, https://www.skyjos.com/fileexplorer/) and play it. I also cannot play it using VLC (2.2.8) in Windows. I use x264 video, AAC audio with MP4 container.
However, if I use CRF set to 23 (or any number), while everything else remains the same, AirVideoHD and FE and iPhone will play it nicely.
Please see log file, screenshots and sample video that is not playable on iPhone.