I tried to set up ldap group to drupal role mapping using the "Convert full dn to value of first attribute before mapping", but the result was that no roles were mapped.
I ran the tests and it confirmed that the groups are there for the user that I'm testing with.
It also confirmed that the filtering was working as I expected, stripping off the CN=, and everything after the first attribute
However the final mapping results section is empty.
If I turn off the "Convert full dn to value of first attribute before mapping" and use the full DN then the mapping works fine.