A few recently-logged-in characters work fine on most API endpoints, but return HTTP 404 on the mounts and pets collections.
works: us.api.blizzard.com/profile/wow/character/tichondrius/%C3%A3zmodan?namespace=profile-us
works: us.api.blizzard.com/profile/wow/character/tichondrius/%C3%A3zmodan/collections?namespace=profile-us
404: us.api.blizzard.com/profile/wow/character/tichondrius/%C3%A3zmodan/collections/mounts?namespace=profile-us
404: us.api.blizzard.com/profile/wow/character/tichondrius/%C3%A3zmodan/collections/pets?namespace=profile-us
works: us.api.blizzard.com/profile/wow/character/hakkar/grulland%C3%A0r?namespace=profile-us
works: us.api.blizzard.com/profile/wow/character/hakkar/grulland%C3%A0r/collections?namespace=profile-us
404: us.api.blizzard.com/profile/wow/character/hakkar/grulland%C3%A0r/collections/mounts?namespace=profile-us
404: us.api.blizzard.com/profile/wow/character/hakkar/grulland%C3%A0r/collections/pets?namespace=profile-us
They both have extended characters in their names – maybe that’s related, maybe not.
Also, if I’m not allowed to post links, how about disabling auto-linkifying URLs in the forum software.
EDIT The examples I provided above now work; perhaps this has been resolved.