I am passing a value for $post_id. In one scenario, I get correct results (although, unexpectedly in array format) while in another scenario I do NOT get correct results. Exact same code, exact same passed parameters.
This points to something in the rwmb_the_value() function not behaving correctly (or something in my hosting environment being corrupted). I have created a separate site (database and WordPress files from scratch) to test whether or not something in my WordPress install is causing this and found the same results.
Again, my guess is that rwmb_the_value() (or other functions or WordPress APIs that it calls) is relying on some global WordPress value being set. As I attempted to explain previously, in the scenario where rwmb_the_value() does not work is a scenario where I'm attempting to retrieve meta data for a post which is NOT the one being displayed (i.e., I'm including data and meta data from a separate post in the post that WordPress is displaying in a normal manner).
