FFmpegSource2 !

[ToiletDuck]

mkv is usually easier to open for filters like FFVideosource2 and LWLibAVSource.
So my suggestion for remuxing to mkv beforehand mainly aimed for the preview issues.

For muxing m2ts, Hybrid can either use tsMuxeR or ffmpeg, so you could also try whether it works better if you use ffmpeg as muxer.

Mkv or m2ts.. it doesn't matter.. it takes proximately the same time to summon filter preview... It only takes longer with LWlibavsource, and whit lwlibav the index file NEEDS to be created from bottom up, every single time i re-open filter preview !!  

Using ffmpegsource2 however, it only needs to create/prepare that index file just ONCE for a filter preview !?!  Even though i close preview, and re-open to check result after i change any filter settings, it doesn't need to recreate / prepare for it time and time again !?  You know why that is ?

It's an 2 egde sword, like i have mentioned before ffmpegsource2 affects output files in a very bad "playback" way !!!
But affects only Low resolution content, not 1080p or 2160p (4k) !!?!

Ps.: m2ts is a mess (trying to calculate the overhead this container creates, before muxing, is just crazy) and in my opinion should never have been used for media files and only for streaming content,...

 
↑ that's one of the main reasons i like to use ts output, to automatically calculate overhead.. 
Even though i know what the overhead is out of my head by now (a few megabytes more or less  ), depending on the Audio (AC3, THD+ac3 ←)  aswell from the source..  


cheers,
TD