Admin plugin multi select error on save

Hi,
I used the following code in my blueprint to define a multi select field:

header.headline.classes:
   type: select
   label: Classes
   multiple: true
   options:
      'class1': 'foo'
      'class2' : 'bar'

The field appears correctly, but when I choose some options and try to save the page, I get the following error message:

Array Array Classes

So I changed the code to :

header.headline.classes:
   type: select
   label: Classes
   multiple: true
   use: keys
   options:
      'class1': foo 
      'class2' : bar
    validate:
       type: commalist

Now the error is gone but the values were saved instead of the keys and the multi select field shows no selected items.

classes:
   - 'foo,bar'

Am I doing something wrong ?

I think Admin currently does not have the logic to show again, once you saved it, the multiple select choices, so it's not ideal for Admin forms.

You're better served with checkboxes now:

header.headline.classes:
   type: checkboxes
   label: Classes
   options:
      'class1': 'foo'
      'class2' : 'bar'
   use: keys