So Seibertron has an article saying that Siege Omega Supreme and Thundercracker may be delayed. Upon checking dates on several sites I think it's safe to say they have been delayed. My preorder for Omega Supreme that I placed as soon as preorders went live is also delayed so it doesn't seem like it's a first batch selling out or anything like that.

Omega and Thundercracker seem like they will be getting released at the start of October now.

https://www.seibertron.com/transform...october/43535/