As the title sais, it seems like all the audio gets always converted from 24 bit to 16 bit on export. This is especially problematic when having a postproduction workflow that includes export of audio to a DAW for dialog cleanup or noise reduction for example. Also in this conversion sometimes artefacts in loud passages are happening (not sure if this is another separate bug)
Thanks for report and sorry for huge answer delay. I don't think MLT can process audio in 24 bits, nor LADSPA filters etc.