A lot of spells such as those from azerite gear (selected azerite spells) and lots of other base spells return 404 responses when using the spells api. Spells from talents and pvp talents seem to work but not base spells for a given class.
/data/wow/spell/255937?namespace=static-us&locale=en_US (Wake of the ashes) works
/data/wow/spell/20271?namespace=static-us&locale=en_US (Judgment) does not. Returns a 404/BLZWEBAPI00000404
Similarly for other classes as well. Tried warrior spells, talents/pvptalents seem to work but base spells return 404 responses.
All azerite power spells also seem to return 404s, example /data/wow/spell/263984?namespace=static-us&locale=en_US (Elemental Whirl)