Tamron (like many others) issued an apology about shortages of the newly released 17-28mm f/2.8 Di III RXD FE lens for Sony E-mount due to high demand (check availability at Adorama and B&H):
Apology and Notice Regarding “17-28 mm F / 2.8 Di III RXD (Model A046) Supply ”
Thank you very much for your continued patronage of Tamron products.The new product “17-28 mm F / 2.8 Di III RXD (Model A046)”, scheduled to be released on July 25, 2019, has a reservation significantly exceeding our expectations , It is predicted that the production number will not catch up with the customer’s request.
We sincerely apologize for the inconvenience caused to the parties concerned, including customers who are waiting for the release of the product.
Delivery to some customers who have already made a reservation may be after the release date. In addition, customers who will be making reservations in the future will also be delivered one by one, so it may be time to deliver the product.
We will do our best to deliver as quickly as possible, so we ask for your understanding.
Update - there are even speculations that the price of the lens could even go up similar to the Tamron 28-75mm Di III RXD FE lens.
Tamron 17-28mm f/2.8 Di III RXD FE lens hands-on videos:
Source: Tamron, via SonyAddict