PKI - Why Root CA is in intermediate CA section?

I can't understand why, when I accept to "install" a custom self signed Root CA on IE browser, the root certificate ends up in the "intermediate CA" section, rather than in "Root CA" section in the browser certificate container (and in Windows certificate manager too, may be both are the same).

Is it a Microsoft strategy, to only display in Root CA section the trusted CA list ? And not allowing the insertion of a "not known" Root CA in this section ?

When using it, I can't see any difference, but there must be an explanation.