WARNING: please back up your important worlds to Dropbox before updating to 2.4!
Thank you for all the bug reports. The odd-shaped and large sun bug is already fixed. How strange can be the celestial phenomena caused by one missing matrix multiplication:

The sun/moon bug manifests itself depending on where you are in the world, so in many cases the sun looks OK. Only when you get to large coordinates the above happens.
I should be soon releasing the bugfix update.
However, the issue with blank worlds list after update cannot be fixed – please backup your important worlds before updating to 2.4.