[Musicxml export] - Some trill lines still not exported

The attached timpani part has lots of rolls notated as trills. At bar 52, there's a long trill line, and it can't be exported into Musicxml. In full score, there are also lots of other trill lines with the same problem, while some of them can be exported. What's wrong? Is this because there are lots of other spanners disturbing Musescore's xml export function? I have to use Python script to get the beginning of the line output as a text, and then add the appropriate braille sign, then guess the ending point to add the ending braille sign.

Regards
Haipeng