All matter is a cognitive ‘hallucination,’ even the brain itself

I guess I'm bothered by both Paul's and Max's points of view on this. They both seem to equate mathematical processing with "experience". But "experience" per the Hard Problem is incommensurate with data processing of any kind. Experience or awareness and other aspects of consciousness like qualia and even agency and thought are inherent properties or aspects of consciousness and in an entirely different and higher extistential realm than matter and energy and mathematics. Their point of view seems to be a reversion to materialism. If "experience" or awareness is only a calculated result, it's nature is calculation, which has nothing to do with consciousness.

That's your own bias. Mathematics only describes the shared relationships of the architecture upon which Experience arises/emerges. Maths is not the architecture, it is a way we can describe something which is hidden.