There must be something seriously broken if musicxml2ly can't convert
this
P.S. I just tried downgrading to lilypond 2.19.84 (from Fedora repo) and
the problem disappeared. So it does look like a regression to me.
Thanks Martin; I’ve opened this tracker page:
https://gitlab.com/lilypond/lilypond/-/issues/5994
It seems weird that such a problem wasn’t caught by our
pretty-extensive test suite, so I’m wondering what might be particular
to your test file. (At any rate, this will need to be added to the
regtests once the problem’s been solved.)