After a thread in Customer Support I was directed here. My WOW1 account linked to my main account is unable to use the portal in SW to Dragon Isle. I’ve completed the main story on the my main account but I am still unable to access this portal as I read it should be unlocked for 58+ once the story quests were completed.
Further on that, my Mage character on my wow1 account was phased at level 64 and could not dragon ride or access quests in SW that leads to Dragon Isle. I was able to overcome this glitch by partying up with a lvl 70 mage friend and enabling party sync so I was able to see them and take the portal they created to valkdrakken.
In addition I recently went through a faction change on my mage on ysera on my wow1 account so I thought this might be some fall-out from that as it’s been less than 12 hours since the faction change.
Support topic Source and discussions.
Dragon Isle Portal in Stormwind - Support / Customer Support - World of Warcraft Forums (blizzard.com)