For performance reasons,[1] when "miser mode" is enabled, as it is on WMF wikis, queries to list=allpages using apfilterredir=redirects and apfilterredir=nonredirects may begin returning fewer than the requested aplimit results before continuation. In extreme cases, zero results may be returned.
This change[2] has just been made and will be deployed in the next few hours so Special:AllPages may be re-enabled.
This is not classified as a breaking change since the API has reserved the right (since 2009[3] if not earlier) to do this sort of thing as it may become necessary.