It might be me, but I find the UI for managing saved streaming settings a little bit confusing. And not so very well documented in the help file ;)
(FEEL I NEED TO POINT OUT THAT I LOVE vMix! anyway :)

Scenario: all profiles deleted.

Enter
URL: http://one.com
Stream key: one
Click "Add" and enter the name "One"
(it would be nice if the input focus was in the name field when Add is clicked).

Now, what's the difference between immediately closing the "Streaming settings" window, and doing "Save and Close". That is, is the profile "One" not also saved when it is added?
(and not to confuse with vMix Profile perhaps it should be "Streaming profile" instead of just "Profile")

Then, open the Streamning Settings window again and enter
URL: http://two.com
Stream key: two
Click "Add" and enter the name "Two"
Just to be sure ;) click Save and Close.

Reflect a brief moment upon what you think you have.
(I thought I had the profiles One and Two with the settings I just entered).

Finally, open the Streaming settings again, drop down select "One", and see what you have.
(I have profiles One and Two with Two's settings).

Something I am missing here?

So, when one clicks "Add" it saves the current/changed settings under the CURRENTLY SELECTED PROFILE NAME,
then adds a new profile with the new name, which is not really added until one clicks "Save and Close"?
That confuse a vMix newbie like me.

A little help on the way would be if vMix after "Add" is clicked asked:
"Save the current settings under [current profile name] before adding a new Streaming profile?"
- for Yes, vMix does as it currently does.
- For No, vMix does not save the old profile, but creates a new profile with the given name and current settings
- for Cancel, vMix echoes "No new profile added" and does nothing.

This way users like me, who enter new settings first and then click Add, would always be on the safe side.