This bug has been around for a long time now. People images also only show up when they want on this screen .

Now I think of it as a mini game of hide and seek, I know the population is there, but are they a farmer or worker, etc.... 

It's a bug from the base version of the game on Epic, unfixed in Supernova. If you rotate between your planets using the left and right arrows some of the buildings disappear. As a work around, if you exit out of the planet window, and directly bring up the planet window they will show correctly.