I’ve been testing Whizbang lately and I can confirm that Whizbang is not working properly. And this problem has been going on since the previous expansion (Stormwind) as far as I observed.
Normally, Whizbang should use deck recipes for current & previous expansion; which is 20 total. They are the recipes you can see in-game when you create a deck. But during Stormwind expansion I have noticed that Whizbang was using 30 deck recipes. (from Darkmoon, Barrens, Stormwind)
(As a side note: Original Darkmoon recipes contain rotated cards, but there is Standard-proper updated versions of them and Whizbang uses the updated versions. Barrens & Stormwind recipes also have expansion-release versions & updated versions; Whizbang uses the release version of Barrens recipes & the updated version of Stormwind recipes.)
Now with the new expansion, the problem is growing. Neither Darkmoon nor Barrens recipes are removed. And there are currently 40 deck recipes in Whizbang’s pool. (from Darkmoon, Barrens, Stormwind, Alterac)
If not fixed, this will get worse by time and we will be unlikely to find any deck recipes from recent expansions.