Hi Armin, I personally experienced this myself. Somewhere between the last BTSync desktop update and the iOS updates, it started doing this. Some folders would sync some files (not all), and there didn't seem to be a pattern to it. I initially created a new Sync folder to sync, and couldn't replicate it. In the end, I just uninstalled BTSync on my iPhone and iPad completely, then installed again and added the folders again and it stopped doing it. Wish I could have helped BTSync devs troubleshoot this more, but I couldn't replicate anymore after the reinstall. Hope this helps.