Investigate why preloading is not working

## Issue Description

in #493 we turned off preloading because it has been found not to work—repress is requesting data even if the store was theoretically set up with the correct values on page load. This is worth investigating because preloading certain collections could improve the initial page render speed a lot in some cases.

Speculation from @rmccue :

> (I also do not know why preloading broke; might be that URLs don’t match properly now, possibly related to ?_locale or something)