Hokkaido Milky bread

Was shopping ard d supermkt & decided to make some changes to d Hokkaido Milky bread recipe by making it a bit more healthy by replacing ½ cup of bread flour with raw wheatgerm.
Wheat germ is d heart of d wheat. It has a nutty flavor & is also cholesterol/sodium free. It’s also full of nutrition. Just 2 tbsp serving will provide:
a) 2g of dietary fiber;
b) 13% of d recommended daily value of folic acid;
c) 10% of d recommended daily value of phosphorus, magnesium & zinc; and
d) 15% vitamin E

End result – a super fluffy loaf but d middle top collapsed. So am not really sure does that means my modification is successful or a failure.

• 500 g Bread flour
• 40g raw wheat germ
• 60 g Cake flour
• 10 g Yeast
• 30 g Milk powder
• 80 g sugar
• 9 g Salt
• 1 Egg
• 250 g Fresh milk
• 150 g heavy cream

Put all ingredients into d ABM & select normal cycle with light crust.