Sync with transcode on some devices only

Hi gang!

I sync my Plex (Windows server) stuff to my iOS and Android devices. On both devices, the sync setting is set to use the original quality. I know that this means that Plex will not generate a transcoded file with a quality different than the original one, but that transcode will take place if needed.

The curious thing here is that there are files that when I sync them to my iOS device, the Plex app just downloads the files (with no transcoding) - which is a dream come true (but that is a topic for another thread) -, but if I sync the very same file to my Android device, Plex transcodes it and then syncs it. The same thing happens with some files which simply download in Android right away, but transcodes in iOS. The majority of my library files were created using HandBrake’s preset “Very Fast 720p30”, which uses H.264/30fps/AAC 2.0/160 kbps in an MP4 container. This is a friendly format, I understand.

Does anyone have an idea of why the same file transcodes for a device and not for the other? Both devices are up to date, top of the line, have great hardware and software capabilities/specs, so the difference is the OS and whatever Plex has done inside each client/app based on the OS… Is there an “universal” format that I can use for creating my files and avoid this issue of transcoding for one device and not for the other?

Thanks!