Format and scaling issue with Symbol editor in Aris 9.6

I have tried to tailor self-defined symbols according to Aris 9 pictogram symbol style and I encounter some issues:
If I use the symbol editor to create them, the scaling is different from the standard Aris 9 pictogram symbols.
The method I use is to export a standard Aris symbol. It is exported in .emf format (No other options). When saving the modified symbol in the .amf format and using the exported .amf file to change the symbol appearance the scaling is not maintained. I have find the right scale by trial and error.

a) Do anyone experience the same issue?
b) Has anyone found a solution to maintain the scaling?

Per Hardangen, Norway