When using a contact list column in a form, none of the contacts appear in the form. This is a serious limitation since we don't want the user to spend time typing in email addresses and then also having the risk of mis-spelling, confusion and frustration.
Do you have a pre-made list of contacts entered in the Column Properties of the contacts column? One of my most-used forms is for a sheet with a Contacts type column, and those contacts do show up as dropdown options in the form.