incrementing in subfolders not working?

The numbering per folder does not work correct. It does not increment, so all files are renamed with 0001. Instead of 0001, 0002, 0003. Is this a bug?
When disabling "Folder" option, the increment is correct, just for test. But I want to increment per folder.
settings
FIlters 12
files: checked
subfolders: checked
numbering 10
suffix
start 1
increment 1
pad 4
break empty
folder: checked
When disabling "Folder" option, the increment is correct, just for test. But I want to increment per folder.
settings
FIlters 12
files: checked
subfolders: checked
numbering 10
suffix
start 1
increment 1
pad 4
break empty
folder: checked