Not sure if this counts as a bug, but when I open the Themed Pet Codex with Display Traits set to "Default", some Blazing Foreworks themed pets show no traits at all. When set to "Matching" they display the matching traits, though.

As far as I can see, this happens for every species except Faelora, Ferrikki, Lunemara, Lupora, Nytekrie and Puffadore.

Checked on a different device and the same happens there.