Re: PVZ2 missing extra levels
It is not a bug. A brief explanation below.
This was a decision of PopCap/EA to make the extra hard levels as a 2-weekly quest on a rota with a good amount of gem rewards.
It used to be 10 levels with 100 gems reward but I guess due to PVZ2 'budget', these 10 levels quest were then cut to be the final 8 levels and the gem reward was also dropped from 100 to 80 respectively.
So the extra (hard) world level are not missing, they just have been repurposed.