A think this is a known issue and solved in the official July version.
This happens when there is pop-up notification at the right which overlaps the button in the alert box. As in your case as you are using the wide format, and in an iframe also.
Although the notification becomes invisible after a few seconds, it still overlaps the alert-box and is"hiding" the (I) symbol for your mouse.
I moved the notification lower to not overlap the alertbox.
Change in pws07/w34_index2.php line 226 from
top: 40px;
to
top: 120px;
Wim