It's strange that when I change the model number, there is no buttons anymore.
Even if I just replace them like this:
origin/250 1366 -152
origin/1044 86 -152
It seems that the origin of duplicated brush somehow depends of this of original one.(I hope you know what I mean)
I can't think of another explanation of why they disappear...
Is there anyone besides Botman, who succeeded duplicating any brush