Steps to reproduce:

1. Create a new project using Universal 3D template
2. Install "Multiplayer Tools" AND "Multiplayer Play Mode" Packages
3. Next to the Play mode button, click on the "Default" dropdown and click "Configure Play Mode Scenarios"
4. Click "" and create new scenario
5. In the "Additional Editor Instances" foldout click on the "" button and add new instance
6. Open the Multiplayer Play Mode window (Window > Multiplayer > Multiplayer Play Mode) and dock it for better visibility
7. Switch to the new Play Mode Scenario and enter Play mode
8. Observe additional Editor instance opens and exit Play mode
9. Open the "Configure Play Mode Scenarios" window again and remove the added item from "Additional Editor Instances"
10. Enter Play mode and observe

Actual results: Additional Editor Instance still opens up. "Player 2" is still shown as active and opens even though it was removed from the list

Expected results: "Player 2" is shown as Inactive and additional Editor instance does not open

Reproducible with versions: 2.0.2 (6000.5.0a9), 2.0.2 (6000.5.0b1) 3.0.0 (6000.6.0a1)
Not reproducible with: 1.6.3 (6000.0.71f1), 2.0.2 (6000.3.12f1, 6000.4.1f1), 2.0.2 (6000.5.0a8)

Tested on (OS): macOS 26.3 

Notes:

• Not sure which package is responsible for the issue or if Editor area is at fault, because testing with same Multiplayer Tools version (2.2.8) and Multiplayer Play Mode version (2.0.2) reproduced the issue on 6000.5.0a9, while did not reproduce on 6000.5.0a8
• On versions where the issue does not reproduce, the Player 2 becomes Inactive instantly once the Play mode is exited