This was caused by a simple typo. With the typo and the example in the description, reloads would be passed in as an empty map instead of reload which would contain the key :reload-macros and the value :reload. Deleting the extra s makes it consistent with the other nearby calls and does the trick.
In a self-hosted environment set up to work with
cljs.js/load-fn, evaluating an expression likefails to request a reload of the code.