When drawing or in drag mode with the Mesh or Tube Light Paint tools, the mesh will update in rendered mode but the emission doesn't show up until the user stops using the commands.
It's due to how the mesh re-evaluates/regenerates with each input command to take parameter updates into account. Blender seems to not fully initialize the lighting since the mesh is being reevaluated. It'll require the update functions to be more adaptive - to only update/clear geometry when necessary.
When drawing or in drag mode with the Mesh or Tube Light Paint tools, the mesh will update in rendered mode but the emission doesn't show up until the user stops using the commands.
It's due to how the mesh re-evaluates/regenerates with each input command to take parameter updates into account. Blender seems to not fully initialize the lighting since the mesh is being reevaluated. It'll require the update functions to be more adaptive - to only update/clear geometry when necessary.