So the data works like this?
Self.Level = 15(39)
Self.EffectiveLevel = 15
Group.Group_0.Level = 15 (this is what is currently used, so the behaviour of the buttons is expected)
If there is no other dynamic data that works correctly I'll just have to work around that and store your unmentored level upon login and check it periodically. If the dynamic data is higher than the stored value update the stored value, otherwise leave it be. Easy enough.
PS: You can check dynamic data values with the /dynamicdata command, no need to dump it to chat channels.