I came back to this character after a couple months to finish the Zandalari unlock, finished the Zandalar forever achievement and pivoted to the tides of vengeance requirement.
I had the quest our war continues, spoke with Sylvanas multiple times and logged in and out but could not get the quest to progress, I abandoned quest while standing next to Nathanos Blightcaller and the quest is not longer available. I have the trivial quests tracker turned on too!
And just realized this post came up as my night elf demon hunter, apologies, it’s actually on my Troll Hunter, Lasardas on Emerald Dream US server