.JAVA extension files not synching ?!

It seems like none of my .java files on the server are syncing. I get an error "server replied not found" but it only happens on files with extension .java.

Error attached below:

05/06/2017 14:23:54, [.......]Assignments_Stats.java, C:\files\OwnCloud,The item is not synced because of previous errors: Error transferring https://p.........Assignments_Stats.java - server replied: Not Found

Has anyone else heard of a problem like that before?