That's strange, which file hosting service are you trying to sync to? (Dropbox, Box, Google Drive?) If you let me know I could try to look into the issue further for you (contact info at gregmcleod.com/contact ). As a possible quick fix, you may also want to try unchecking the "Compress Data" checkbox on the syncmarx options tab and doing a force push of your bookmarks which may trick it into working again (I've discovered the compress feature can sometimes cause issues)