Using Town Portal Breaks Quest NPC AI

Happened to me with Lachlann in Act 1 Graveyard and just now again with Asala in Act 2.

In act 1, I used the Town Portal to dump some gear after opening the gate to Lachlann's family, he ran ahead but when I got to him, he just stood at the graves.

In act 2 I used the Town Portal to disenchant some gear, came back and Asala was standing where I left her, doesn't follow me, and won't activate the second level to open the gates.

Creating a new instance fixed both cases.