[HELP] muxing won't start/processing stuck at 100%

[Iwan]

I'm trying to frame interpolate a 25fps video to 60fps. 

Windows 10 64bit
x264
55000 bitrate 4.2 restriction
Avisynth interframe to 60, smooth, smooth

[Selur]

Assimiliert ng you are trying to create an mp4, try whether using FFmpeg instead of MP4Box helps. ( unser Output->Container Settings->Mp4 Settings)

Cu Selur