@futr_vision -
Regarding the ComboBox with this in the Items property:
Distinct(Filter(Tactics, StartsWith('Tactic Name', Self.SearchText)), 'Tactic Name')
The Distinct function will return a single column Table named "Value". In the Update property of your DataCard, I assume you have:
'Your ComboBox Control'.Selected.Value
On the DefaultSelectedItems property of that ComboBox, you will need:
{Value: Parent.Default}
Regarding the ComboBoxes with these in the Items property:
Sort('Campaign Types','Campaign Type Name', SortOrder.Ascending)
Sort(Filter('Campaign Sources', 'Campaign Type Name' = CB_CampaignTypeReview.Selected.'Campaign Type Name'),'Campaign Source Name',SortOrder.Ascending)
In the Update property, I assume you have:
'Your ComboBox Control'.Selected.'Your Column'
In the DefaultSelectedItems property for both ComboBoxes, you will need:
LookUp(
'Campaign Types',
'Your Column' = Parent.Default
)
Explanation:
Your ComboBoxes which do not use the Distinct function in the Items property return a Table of records, and it is important that the Items property of your ComboBox control and the DefaultSelectedItems property share the same table schema.
Typically, we create a Single Line Text Column in SharePoint, and then insert that Single Line Text Column into an EditForm control. We then remove the Text Input control, and replace it with a different control (in your scenario, a Combo Box control). We also set the Update property to point at the selected value from that Combo Box.
However, if we add the following into the DefaultSelectedItems property, we could see the following error:

The ComboBox is expecting a Table. As a workaround, we can force a Value into the DefaultSelectedItems property using:
{Value: Parent.Default}
However, this approach does not work with Dataverse. As you have noticed, if you add a Label control and reference the ComboBox , even though a value is “displayed”, the Text will still return blank. This is will because we are supposed to pass a record into the control because that is what the ComboBox control expects.
To supply a record into the ComboBox, we can force the correct record into the ComboBox using the Lookup function.