It seems that box doesn't handle datasets exported from packages:

> box::use(datasets[mtcars])
Error in attach_list(spec, names(mod_exports)) : 
  Name “mtcars” not exported by datasets
> datasets::mtcars # Works fine

Perhaps the problem is lazy loading of data? This happens on other packages as well, e.g. box::use(zipcodeR[zip_code_db]).