City of hope bug

I am trying to compete city of hope, second part earn your exalted markings mastery...in Auric Basin, Arrow head vale/If I am out of the area the waypoint location is marked with the green star on map. But when i enter the area via the nearest waypoint the green star disappears and Ruka the Wanderer is not at the location near the gates to Tarir as marked on the out of area map, so can not progress as can not get to waypoint. Sage welni is nearby.tried adding -prefreset to gw2.exe as suggested on help desk but this did not work.I am level 80 mesner ventari.

Have you already earned your Exalted Markings Mastery? You need that before you can continue.
https://wiki.guildwars2.com/wiki/City_of_Hope

Done first part and earned mastery. The quest marker now points to Ruka but when i arrive at the nearby waypoint the quest marker disappears.

Well, you can try a -repair of the client.
Try starting a different Story Episode and return to this Chapter.Try completing the Story with a different character.Try to find a friend/guildie/other player to play the Chapter with you in the party.

Good luck.

Thanks how do you repair client? tried adding -prefreset to gw2.exe as suggested on help desk but this did not work.

Same way. Add -repair instead.https://wiki.guildwars2.com/wiki/Command_line_arguments

thanks. tried it to no avail