caches.keys is empty, although there are cached endpoints

Question

I have an ajax endpoint that is cached (devtools > network shows it as (disk cache) - top of the image) Yet, when I try to list all cached endpoints in the browser, I get an empty array (bottom of the image)

caches.keys().then(function(keyList) {console.log(keyList)});

What am I missing here?

I am trying to work an invalidation technique for asp.net core's [ResponseCache]