Beam target of ender crystals used for ender dragon spawn sequence do not update after unloading

When you unload the ender crystals used for the respawning of the ender dragon for example by killing yourself and then loading them again the respawning sequence will continue but the BeamTarget of the ender crystals won't get updated.

How to reproduce

1. Kill the ender dragon
2. Start the respawning sequence
3. Kill yourself or unload the portal
4. Come back to the portal

The sequence will continue but the ender crystal beams do not change.