Getting a lot of error messages inside the trader

[tender lava]

Game was working fine but all the sudden when my friend's or I enter Trader Rekt, we can't see each other moving, I become encumbered, and things outside of the trader change. As soon as we walk outside the trader, it goes back to normal.

[median vine]

Did any of you bring an NPC follower to the trader area?

[tender lava]

Yes

Multiple