Converting a light to Spawnable removes it from Light Mixer

This is a regression as the issue does not occur in //UE5/Release-5.1 @ CL 23901901

1. Open Light Mixer tool (Window > Light Mixer)
2. Add in any light 
3. Create a level sequence > Open and add the light to the sequencer
4. Right click on the Light in the sequencer track > Convert to Spawnable

Expected Results: Light is converted and also remains in the Light Mixer window

Actual Results: Light is converted but is removed from Light mixer window