I created a new QoS Class through the old-look-a-like SmartDashboard (the one is selected):

but when I try to add it to the external interface to set the inbound/outbound rates and stuff, the SmartConsole is unable to find it:

I also tried to do it over the GuiDBTool (replacing one of the class already in use) but:

and tried too over dbedit CLI with also no success
Maybe a bug?
Thanks!
P.S.: in the second screenshot the caption title of the windows is wrong, because I selected to create a new DiffServ class, not a Low Latency one, also a (minor) bug?
P.S.2: a clarification: I need to create a new DiffServ class because we've enabled the Threat Emulation on cloud and when arrives a mail with a large attachment, the emulation keeps stucks uploading the file to the cloud