Forge Server v1.16.5-36.0.21
Immersive Portals v0.14-mc1.16.4-forge
To reproduce, build a bi-way portal between two points. Player A & B both start on one side and can see each other. Player A passes through portal, once player B passes through portal, player B becomes invisible to player A. Both are still in the same game world and can interact, but player B will remain invisible until they relog. Player B can see player A without a problem. Passing back through portal does not make player B visible again.
Forge Server
v1.16.5-36.0.21Immersive Portalsv0.14-mc1.16.4-forgeTo reproduce, build a bi-way portal between two points. Player A & B both start on one side and can see each other. Player A passes through portal, once player B passes through portal, player B becomes invisible to player A. Both are still in the same game world and can interact, but player B will remain invisible until they relog. Player B can see player A without a problem. Passing back through portal does not make player B visible again.