Because of the important data files that were involved, I will not try to reproduce the problem again on those machines, but when I have the time I will try to do a large new sync with logging on with other machines and see if the problem reoccurs. The problem I described with my picture folders, have not occurred again, probably because there are no large (in files quantity) sync/index batches again. Maybe CardinS2U can reproduce his/her problem quicker with logging on.