This year I have had several occasions when cakes were not cooked evenly. At first I thought the problem was with the oven so purchased a separate thermometer which indicated that the oven was at the correct temperature.
The middle of the top of the cake would be uncooked and only discovered when levelling the cake for decorating. skewer inserted before removing from the oven came out clean.
Yesterday, the same think and when I layered down through the rest of the cake there were random uncooked bits and a whole thin layer at the bottom that was uncooked.
I have discussed this with friends who are also bakers and a number of them have had the same problems recently, we all used different brands of flour, some have gas ovens and some electric (with and without fans).
I know the cake is mixed evenly (checked that). Has anyone any idea what could be causing this? We did wonder if last years excess rain could have caused issues with the wheat and subsequently with the flour.
What size of cake pans are you using? Have you tried greasing a metal rose nail in the middle of your batter which makes for more even baking? Do you put your rack in the middle of the oven? Does this happen with the same cake recipe? Maybe a different cake recipe may work better. Hopefully some of these cake experts can answer as to why this is happening. I know it has got to be frustrating but I am sure that you will figure out what to do soon to fix this situation. Good luck!!! Keep the faith!!!