It looks like there's another issue with flagging in the 10k user tools. Here is what it looks like:
As you can see, the container for the content seems to be the cutoff for where I can see the dialog. The background of the site seems to be above the flag dialog (which is bad).
Unlike the grey box issues over the buttons, this
<div> doesn't seem to have a z-index property:
<div id="popup-flag-post" class="popup" data-postid="19489" style="position: absolute; top: 1984px; left: calc(50% - 350px); display: block;">