In latest version (8.2.1) if u have form combo with a template and u have already selected an item the input field changes its height in order to match the html template height which is fine.
HOWEVER
If you click again inside the input field (a reason for that may be that u want to change the selected item) the input element displays the raw item value( not the template) which causes the input height to go back to normal height BUT the dropdown stays detached from the input field and makes the interface look bad.
It would be really rational and very easy to implement a config option so user decides if he wants to display the template inside the input field or simply the value.