Hi,
I experienced that UMC adds additional quotes in the Samba permissions field write list.
I enter @"internal IT" and UMC stores it as @\"\"internal IT\"\" which gets unescaped to @""internal IT"" which in turn gets encoded to @\"\"\"\"internal IT\"\"\"\".
Additionally, the whole value gets enclosed in double quotes. According to the Samba documentation that does not seem to be necessary but I did not dig too deep into this. The valid users field seems to be syntactically equivalent and UMC does not add double quotes there.
Bests,
Masin