Choices are seperated in SharePoint using
;# instead of
;. Setting your default value to
DOMAIN\account1;#DOMAIN\account2;#DOMAIN\account3 should allow you to set multiple default values.
Alternatively there appears to be a solution posted on Technet (link) that may work.
In case the link doesn't work in future here's the contents of that:
Hi Thank you for responding. Sorry for not being as clear as I hoped
List A is a customized form library with the people picker as a
promoted field from the form. Not build from the library. List B is a
document library, and I am actually creating a new item in this
library where my default content type is a customized document set.
So my workflow creates an item in the doc library, which is by default
a document set. I then set the properties of the document set from the
work flow like you show above. But instead of UPDATE, I am using
CREATE. This works perfectly fine and how I want it to, except for the
people picker with multiple selections.
I found a work around where I have a text field with a default value
(done in InfoPath)
'concat(pc:AccountId, "; ")'), "..") This sets the text field with the
multiple users with the display name. I then use this field to set the
people picker, and it works perfectly.