The last 3 orders from Quadratec were in stock when I purchased then out of stock by email 2 days later, same thing you seem to get 2 separate emails which is confusing! I dont have much choice being in Australia but I cancelled 2 orders and waited for one. They give you back your funds without any problems and at least they tell you if its out of stock or there will be a longer wait albeit after you have paid for an item displayed as in stock.
Like some others I use RockAuto they ship pretty quick even half way around the world and it shows inventory when you choose the part.
Get used to delays, life is never going back to what it was, even some USA made parts have Chinese components and now importers are being forced to pay for entire shipping containers so they cant just mix & match from different manufacturer's like they could pre plandemic. Maybe not your item in case but an importer would have to fill a container with blower fans or other items from the same manufacturer where in the past they filled it with parts from many manufacturers, the reason is not just inflated container prices but factories in China and other S/E Asian countries are in constant lockdowns worse than Australia and all the cheap slave labour go back to their villages because they are not getting paid causing a labour shortage when the factories re open.