Freeze issues on Nexus 5 or Lollipop
If you experience unresponsive device while syncing, try disabling md5 checksum option for folderpair. Why this happens is still unknown, but probably has to do with the new ART runtime in Lollipop.
Writing to external SD card in Android 4.4 Kitkat
Because of changes in the Android OS, it is no longer possible for apps to write to external SD cards on some devices which have been upgraded to Android 4.4 Kitkat. Currently there are no viable workarounds.
Please see a discussion of the issue here.
Please see how to apply root fix here.
Note: On Android 5.0 this issue should be resolve by using storage access framework. If you have a Lollipop or newer device, grant FolderSync external SD card access on the settings screen.
NetDocuments and file names with special characters
Problems with non-ASCII characters in file names. NetDocuments is aware of this issue and it will be fixed in the next release of their server software.
Samba/CIFS and leading/trailing spaces in name gives problems