Main quest line for Silverpine Forest gets completely bugged out at Transdimensional Warefare: Chapter III.
The NPC “Archmage Ataeric” does not appear at the given quest location, but rather he appears back inside the Forsaken Front zone and does not move towards the quest location. If you try to approach the NPC he vanishes.
This is the main quest line from Sylvanas for the entire zone and it breaks the zone experience. This has been reported for over 3 years and it is not the only quest with similar issues in this zone. Sylvanas also gives a quest earlier to travel to Fenris Island where the NPC supposed to follow you also phases in and out - making the quest impossible to complete without grouping with and party syncing with someone who has never done it.
This is an important zone - please fix this issue.