I did test on Dgraph in Ratel and got similar results. So this issue is not specific to the graphql endpoint.
Edit: I also just read through the docs and while one could put this limitation together it is not explicitly stated anywhere that I found that these two used together provide odd results.
I was really looking forward to use @cascade more after it gets parameterized, but will not be able to unless there is someway to control pagination after cascade.
Pagination allows returning only a portion, rather than the whole, result set. This can be useful for top-k style queries as well as to reduce the size of the result set for client side processing or to allow paged access to results. - Query Language - Query language
With the
@cascadedirective, nodes that don’t have all predicates specified in the query are removed. - Query Language - Query language
^ This leads to the understanding pagination first then with those results do a cascade.