Same issue, tried various different conditions of declaring the war on venice and the mission tree never swaps. I backed up the mission file and tried to edit some conditions to try and make them appear under other conditions and eventually tried to make them appear consistently, things that have helped me work through bugs in mods in the past, but I couldn't get the missions to appear no matter what I tried. The league of venice also didn't work correctly and people such as the emperor and spain didn't join the war, just venices regular allies. Fortunately it doesn't seem too immensely gamebreaking but it is definitely unfortunate to miss out on the flavor