Rotella has had some of the worst availability among the others. WM “in store” is mainly T4 15w40 and SAE 30 while the other brands are stocked in all their normal flavors.
Extend beyond WM and Rotella looks about normal as do others.
It could be that since the vast majority of Shell's sales are through Jiffy Lube, and with some availability concerns, they're giving Jiffy priority with stock. The occasional batch makes it to the shelf.