No Character Portraits and Character Tokens showing

Hi Folks,
Playing D&D 5E. I have a player who went dual monitor and logged in as "local host" for one session in one campaign. He is now logging in using one monitor in that campaign. Since doing so, he no longer sees character portraits or the character tokens at all in this specific campaign. He does see the monster tokens and the map. This is the only campaign that has this issue out of the three. Two other campaigns display normally. Also, whenever anyone moves the toke (DM or player), he gets the attached message. No one else is getting these messages so we figure it is tied to this issue. Any help as to how to resolve this is appreciated.

localhost only works on your (the GMs) computer.
If the player is on your computer then localhost will work - otherwise it wont.

Delete the character from the Combat Tracker and Map and then add them to the CT and from CT to map again.