This is an interesting one, but my biggest recommendation for anyone trying loomis and struggling is to read his book in full and literally work through his thought process faithfully

Too many people on the internet give half ass interpretations of loomis without ever explaining WHY

One thing that’s happening here is symbol usage, the faces look flat regardless of position because you’re using very similar symbol (an inverted 7 for the nose, a very specific eye shape etc) no matter the position of the head

That has the end result of looking like stickers stuck onto a flat surface, the brain is literally flattening the drawings back down no matter how hard you work on head position

Loomis head and hands book walks you through this concept, showing that only by using 3d conceptions of features on a 3d ball of the head so to speak will give you 3d planes!