I think the reason is in version 1.5.3 it has problems like this.
Checkout page not work in versions 1.5.2 and 1.5.3. I had to rollback to version 1.4.8.
Be especially careful with version 1.5.2!
It completely simulates the work, but orders are not saved and you will not see them in the admin. panels (you will think that there are simply no new orders)...