Is the "AssignedTo"column a Person type column in your SP List?
Based on the third screenshot that you provided above, I think there is something wrong within the value you typed for the 'DisplayFields' property of the ComboBox (DataCardValue7).
On your side, you should configure your AssignedTo ComboBox as below:
So the DisplayFields property of the ComboBox should set to following formula:
In addition, there is an known issue with the Person field ComboBox in a Edit form -- when you click the Person ComboBox, these available options would not be shown up as list, only when you type some search text within the ComboBox, these related person option would show up:
Please try above solution, hope it could solve our problem.
Community Support Team _ Kris Dai If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
Thank you for your reply. I tried different data card options but yesterday I was unable to make changes on PowerApp canvas as there is an error that I need to submit to support. I appreciate your input and I figure that there was an issue with Person filled combo box populating the field.