Is there any reason why Store might not be logging transactions with Google Analytics apart from JS being disabled/unavailable? We have some orders not showing up in GA and the client is keen on identifying the underlying cause.
Store relies on the customer landing on the payment complete/invoice page for the Google Analytics e-commerce tracking to work.
Depending on which gateway you are using (especially if it is an off-site gateway), some customers might simply close their browser after they see the gateway's "payment complete" page, and not click through to your final invoice URL. If that is the case, there is no way for the orders to be reported to GA.