For the time being, using field_list seems to allow the character pages to load (see this post - https://comicvine.gamespot.com/forums/api-developers-2334/cant-access-character-page-1977917/?page=1#js-message-20993583).
e.g. for Batman (1699) I am able to specify everything but story_arc_credits and/or volume_credits.
Sort of a pain, but
seems to work for now.