Since the launch of 12.1, I haven’t been able to consistently interact with certain NPCs in either my Alliance or Horde Garrisons (I have 3 of each). Specifically the Quartermasters, which will sink into the floor or just not be there at all, but also the Work Order NPCs. I have also noticed other NPCs randomly missing. The Quartermaster offering the daily armor quest is especially a bummer. I saw a similar bug report on the EU forums, but couldn’t find one on US, so I apologize if this is a duplicate. Can confirm this is happening across all 6 of my Garrisons, to varying degrees. Sometimes logging back in fixes it, sometimes it doesn’t. but it then repeats again upon next login.
FWIW, I log into all my Garrisons at least twice a day.