Hi @Anonymous,
Could you please tell me how you set the Items property of the Listbox?
Do you want to check the Checkbox if the user is selected?
If you want to check the checkbox when the right use is selected in the Listbox, please check as below.
Listbox2 Items:
ForAll(Tracking.IfYesEnterMailID,IfYesEnterMailID.DisplayName)// IfYesEnterMailID is the Person column
Checkbox 1 Text:
First(ForAll(Tracking.IfYesEnterMailID,IfYesEnterMailID.DisplayName)).Value
Checkbox 1 Default:
If(Checkbox1.Text in ListBox2.SelectedItems,true,false)
