Reply To: select advanced in Group showing: "Warning : Invalid argument supplied foreach"

Thanks so much Anh, I didn't know that groups will affect how to display fields on the website.
Now works very well.

One more thing is that when adding multiple keys/values to select advanced the Metabox Builder does not create an array but a unique value, if I input the following on the options field:

Red: red
Yellow: yellow
Blue: blue

The Buuilder creates this and not an array:

'options' => 'Red: red
Yellow: yellow
Blue: blue',