there is more to it than that

[keannu]

What does "it" and "that" each mean? "that" seems to mean "coffee itself" in the previous sentence, and "it" seems to mean the whole previous sentence. Can "it" substitute a sentence? I feel the distinction between "it" and "that" is quite ambiguous here.

ex)For many people, a cup of coffee in the morning is part of their daily routine. If they don't have it, the rest of their day feels incomplete. Obviously, part of what makes a cup of morning coffee so enjoyable is the coffee itself. But apparently there is more to it than that. In a study, researchers had people drink a cup of coffee in their favorite mug...most people enjoyed it more when they drank it from their favorite mug....

 

[keannu]

As I know, "it" usually refers to previously mentioned nouns, so I wonder how it can refer to a clause like "what makes a cup of morning coffee so enjoyable .".

 

[JMurray]

Obviously, part of what makes a cup of morning coffee so enjoyable is the coffee itself. But apparently there is more to it than that.

there is…
more to it = more to the matter of "what makes a cup of morning coffee so enjoyable".
than that = than the explanation given here i.e. "the coffee itself".

not a teacher