I worked on a powerpoint file for a few hours today, moved it from my documents folder to a resilio sync folder (sync pro 2.4.4).
Tonight, when I opened sync, it says that file is locked. I closed that file hours ago. This "locked file" message happens frequently with colleagues and myself. Files are said to be locked but sometimes appear fine to others. Usually closing and restarting sync removed the locked file message BUT one should not have to stop and restart sync every time one works on a file in sync folder.
Hopefully your team is actively working on this issue.