SelectMultiple with default selection acts like a RadioButtonGroup

[ecircenis]

if I have a single defaultValue set in a selectMultiple and then expand and want to select a second option, it first de-selects my defaultValue. Essentially, it treats it as a radio group and not checkboxes.

You can see this occur in this design: https://designer.grommet.io/?id=test-edgar-circenis-hpe-com

The GreenLake option is selected by default. If you expand the control to also select AWS, it first de-selects GreenLake.