Tried with different layer combinations and found some interesting differences. The issue seems to arise only when the following layer in the sequential is a ReLU. Output from different models being run:
Whole Model 0.7501
Sequential(Conv2D) 0.7446
Sequential(Conv2D, ReLU) 0.7501
Manual sequential1 (Conv2D, ReLU) 0.7446
Manual sequential2 (Conv2D, ReLU) 0.7501
Sequential(Conv2D, Conv2D, ReLU) 0.7446

I can’t figure out how putting a Relu after the convolution would change the output of the convolution from the hook. Even manually running the sequence of layers seems to exercise the issue…