My two most recent flops were the Golden Genoise and the Perfect All-American Chocolate Butter cake. It was my first attempt at the genoise. The egg yolks never attained the increased volume they should have when mixing. Similarly, the chocolate butter cake never attained the volume either - based on the final level of the batter in the pans.
My trouble more generally is that over the past 9 years, the cakes I bake never attain the appropriate height (although it has been acceptable in the past, certainly better than the last two attempts). I am reading details in the Cake Bible. I will pay closer attention to temperature of the butter and the eggs. Almost certainly they were too cold when I attempted the recent Chocolate Butter cake.
But I suspect a more fundamental problem with the structure that needs to be solved.