The endpoint descriptor and the endpoint configuration looks good.
Can you try an OUT transfer using the Control center application and see if you are able to make the transfers successfuly.
Here in the descriptor I have seen that you are requesting 3 ISOC packets in a single uFrame. When you test with control center start with 1 ISOC/uFrame(db 04h Max packect size (MSB)) and test it.
And is the IN endpoint configured as Bulk or ISOC?