I have a multiple enumerated site parameter.
This parameter already has valid values.
But on editing the site, the combobox of this parameter is empty.

The value sent by the server is like this:

"my-parameter-name": [
     {
         "value": "first-choice",
         "label": "The first choice"
     }
]

And the widget used seems to be edition.boxselect.

There is nor JS error nor log error.