Inverse Kinetics Is Not Working in a Multiplayer Game

I'm developing a multiplayer app for both the Oculus Rift and Quest using Unity, Photon PUN 2 (Photon View, Photon Animator View, etc.), and the VRIK feature of Final IK (from the Unity Asset Store).  In terms of humanoid model avatar motions following the player's hand and head motions, for the Rift everything works fine except that the other player's avatar is in its default state (in my case with the arms elevated and extended away from the body) and completely motionless.

For the Quest everything's fine for the first player until the second player enters the room, at which point the hands of both players' avatars lock up and can't be moved.

Any insight as to how to resolve these issues will be greatly appreciated.