You said you used 1/2” oak plywood under the homasote, is that correct. I question why you would do that, first of all it’s very expensive and it is finish grade plywood, like for cabinets, not meant to be used as an underlayment. I wonder if the glue you used didn’t adhere so well to it.
You can prob fix your issue with some well placed screws I would think. Kerf the homasote if necessary. It’s fixable.
