Have a -400 bar full score created in Sibelius and converted to XML. The first part of the import to Dorico looks fine and after a bar 200 or so, there are no notes. The dynamic markings are still showing but not anything else. There doesn’t appear to be anything wrong with the file itself. I tried converting the file twice.
Have you tried to convert with the Dolet plug-in?
Have you found the bar that causes the problem? Sometimes it’s easier to delete it and renotate it in Dorico than trying many things…
Babe8, if you zip up and attach the MusicXML file here, or email it to me at d dot spreadbury at steinberg dot de, we may be able to take a look and figure out what’s wrong. Normally this happens when a duration is encoded incorrectly in the MusicXML file, often because a tuplet is set up wrongly.