EDIT: See Below.
Same problem for me that no download occurs. Just I click the Download button in the announcement, and the announcement at top disappears. No other processes. No messages. Same problem whether in normal mode or incognito mode. When I close browser to try again, I find only a message, "dragon has crashed". For me, the Download-Install problem has NOT been fixed.
Windows XP sp 3, Comodo Dragon 18.0
EDIT: Success THIS Way:
I finally succeeded when I opened the main menu (from circle dragon-eye button), chose About Comodo Dragon, and there was a button "Download" and "OK", so I chose "Download". This download took about 4 minutes. Next this About box showed options for buttons to "Relaunch and Install", or "OK". I chose "Relaunch and Install". Then Dragon disappeared and only desktop was shown, occasionally mouse pointer and hourglass blinked. Nothing else. Wondering what else was going on, but seeing nothing, I doubleclicked the desktop Dragon icon,... and find that now I have version 18.104.22.168, so this is good.
The update installation needs better user messages.