I found 3 bugs: The first is easy to recreate - Neptune will look like an ice planet if its in mid collision with Jupitar, Even if it was rocky, it wouldn't be solid in such an event.
How to recreate
1: Make new simulation
2: Add a Jupitar
3: Add a Neptune
4: Watch the collision play out from start to finish
The second is VERY easy to recreate: Gas giants, when very hot, will appear as if there brown dwarfs and have the star glow around them.
How to recreate
1: Make new simulation
2: Add any gas giant
3: Make the gas giant rediculously hot.
The third one is that, If you make a planet out of water, sometimes it will appear solid, even if its temperature is above freezing AND has an atmosphere. How to recreate
1: Make new sim
2: add any planet
3: Change the materials to be completly water
The 4th is also related to water - If you make a planet that has some islands, but still has water, And heat it up, It will sometimes appear as an ice planet, even though it should look like a gas giant (because its steam, steam is a gas) How to recreate
1: Make new sim
2: Add any planet
3: Give the planet enough water to have some, but sparse, islands
3: Heat it beyond boiling.