How to restore VIP mailbox on Mail

I have accidentally deleted the VIP mailbox on macOS Mail app. Searching on the user guide I haven't found any way to restore it.

I've tried to set a friend as a VIP hoping that the box would reappear: in doing so the app crashes.

I've tried to doing the same on the iPhone Mail app, after which trying to open the Mac Mail app it crashes.

Emptying the iPhone Mail VIP box and reopening the Mac Mail app it starts working normally again.

Is there a way to recreate the VIP mailbox or, eventually, totally reset Mail app in order to see and reuse again the VIP box?