Bug or by design?

In Defense+ if “Treat unrecognized files as” option is unchecked unrecognized files are not added to unrecognized files list.

If by design, is it really a good idea? I mean aren’t you supposed to know what programs (still) aren’t recognized even if you don’t use auto-sandbox?

im pretty sure this is by design. i uncheck this option on my system. it shows all the HIPS alerts for unrecognized programs which is what i want

And if “Treat unrecognized files as” option means restriction level for applications running in Sandbox, why it doesn’t placed at the Sandbox Settings tab?

It’s by design. When you turn of the sandbox unrecognised files gets handled by user assisted by D+ alerts.