Theme Datalist Control Behaviour is not consistent between browsers

Issue: Behaviour of the Theme Datalist Control is different in Firefox compared to Chrome, and Edge.

Examples of this include;

• In Firefox a user needs to perform an extra step by clicking twice (or once and using the arrow keys) to see a list of options, instead of a single click.
• In Firefox a user must perform an extra step by clicking off the control/hitting enter for the selection to be made, instead of single click or pressing enter once.