Drop Downs Not Selectable on Mac Chrome (Stuck on first option)
I’d suggest using Mendix out-of-the-box functionalities whenever possible. There’s an option when you edit a reference selector or a drop-down called “Empty option caption” (under General) that allows you to customize the text of the “Blank space” option.
I agree with Abdullah's comment. Additionally, setTimeout() seems more logical than setInterval(), since the latter will cause that your function is called every second.
Did you go this route to add placeholder text to your drop down? If so, you can check out the Dropdown selector widget.