I have discovered a bug with positioning of the drop down on Modal pages. Specifically I am using Blazored.Modal, and if the main page is scrolled below the original max height then any drop downs will populate at the bottom of that original max height. So if I scroll down a little, the drop down box displays a little too high. If I scroll down a lot the drop down box displays above the top of the screen where users cannot see it.
Below is an image with the page slightly scrolled down. You can see how the departments drop down is appearing above the department box.