Alex wanted to learn more about the aura, trying to get to understand it at a deeper level. He wanted to use that understanding to help improve his Intent. He had been through this twice before, so it shouldn't have been that difficult.
However, as he tried improving his Intent through the painting, he realized that he needed to go deeper into the mysteries and try to learn them all. He fell into a lull as he did so as he began understanding more and more of the aura.
There had been something about the aura that had confused him since the first day he had placed his feet on the stairway. The pressure he felt was not the same as what a normal cultivator could place upon other weaker cultivators.
Those were aura that directly came from their cultivation base and their strong Qi, placed upon someone with a weaker cultivation base and weaker Qi. This was different.