Windows has special behavior where it considers filenames that are longer than 8 characters to be equivalent to shorter 8 character names in some instances. For example a file called 'January Report.doc' would be considered equivalent to 'JANUAR~1.DOC' if they were in the same folder. The latter is always 8 characters followed by a 3 character extension (also known as an 8.3 file name).
If you use Desktop Sync on Windows and a user uploads a 'short name' file to the cloud, it will conflict with files which start with the same characters in the same directory on other users' machines and prevent the files from synchronizing properly.
There are two steps to resolve and ultimately prevent such issues:
1) When you see conflicts that arise from matches with files in the cloud that have the 8.3 naming convention you can resolve the conflict by renaming the files, with the 8.3 naming convention, in the cloud with their full name (if the name matches an existing name, you'll be prompted to merge the two files so they appear as two versions of the same file in the cloud - the version which was modified more recently is considered the latest version). This will ensure that the file is synchronized properly.
2) To prevent this situation from arising, find out which users machine uploaded the 'short name' version of the file and disable the 8.3 file name creation mechanism on the machine by following the steps in this article: https://support.microsoft.com/en-us/help/121007/how-to-disable-8.3-file-name-creation-on-ntfs-partitions.