Hi,
Configs done at /md level should get pushed down to lower levels ( customer groups & WLC's)
Please check if you still have any pending changes ( WebUI Right hand corner)
Moreover the CLI outputs attached from your end shows that server-group for mgmt auth is configured at MM level rather than MD level
Please log in to CLI and share the following output:
Aruba[mm] #cd /md
Aruba [md] #show configuration pending
Aruba [md] #show configuration committed | begin "aaa authentication mgmt"
Aruba[mm] #cd /md/<name of group at first level>
Aruba [md] #show configuration pending
Aruba [md] #show configuration committed | begin "aaa authentication mgmt"