If you cannot see Shandris in Valdrakken City it’s because she is in Ohn’ahran Plains for the Fire Season quest in the bottom left corner. You must do that story quest to free that NPC, then go to Valdrakken complete Captain Drine quests.
You have to complete all Drine’s quests at South Gate Pass as well amd then when you return follow the story until it clears having to meet Shandris.