I see others are have missing Block button on the pop up when firewall is in stealth mode. While calling into tech support and getting told that they have not anybody report this issue ever on the new GUI I searched and I saw others in this discussion asking what happen to the block button.
Well I found it and even reported it to tech support. Hopefully they fix the new GU soon.
Until then when the pop up shows, click the top of the pop up and the hit the tab key until it high lights over the buttons yo will the see it shift every thing and block will highlight.
Support you need to fix this new GUI and resize the pop up so all buttons can be seen. I have included screen shots of before and after using tab key.