Urs Liska-3 wrote
210 × 17428 mm
That's interesting… On my computer (Windows 10 64 bit), Adobe Reader XI
shows 210 x 5.080 mm.
But that seems to be a limitation of the Adobe Reader.
Considering the PDF (tested with 2.19.55, 2.19.82, 2.21.0), it says
<</Type/Page/MediaBox [0 0 595.28 49401.7]
And that, converted into millimetres, exactly matches the 17428 mm you
found.
In any case, the output page size is far too long and this is a bug of
#ly:one-page-breaking in combination with ChordNames at the end.
All the best,
Torsten