As requested by GM Miss, i am creating a thread in the forum.
I believe there is a bug related to the Arachnos building in Mercy Island and mission waypoints. It can be reproduced playing the Seer Marino arc from Ouroboros "Oh, Wretched Man!".
After completing the mission "Get records, leave no witnesses" located inside the Arachnos Building, when you call your contact from inside the arachnos building, you get an invalid waypoint as shown in the video
To complete the arc, dont call your contact after completing the mission "Get records, leave no witnesses". Instead, select Seer Marino (you will get an invalid waypoint) and go to her (use the local map to navigate). Talk to Seer Marino and get a valid waypoint to the next mission.