Once they turn into ashes after the Heatwave ended and not tamed, mark the spot its ashes landed with something you can find easily. Now just toss down some oil jars around where the ashes fell. Throwing ten at the exact spot will destroy the oil. When oils were placed around the spot, light it up with any sort of weapon or a dino that can create fire; such as flame arrows, flamethrowers, pheonix and finally the FIRE WYVERN(Alpha will work too, but it won’t be easy). Once you light the oil on fire, they should disappear after some time, when they do disappear, replace the oil on the similar spots and light them up. Repeat this progress until tamed. Once tamed, they should be bugged out and won’t have any animations. To fix them just simply upload the pheonix to the Ark creature datas through a supply drop or an obelisk. Any colors or obelisks will work. After uploaded, just download the pheonix back. And there you go, you got yourself a pheonix. It should also take around 100-200 jars.