As the title says, giving candles a texture with transparent pixels, renders it as black

I expected it to work properly, just as all three torch types and sea pickles. But when I gave lit candles a unique model with fire animation it rendered the unused area of the fire texture black.

Candles are a non-solid block with no side being a full 16x16 square area. They never cause any culling on blocks around them so it makes little sense to disallow them from having transparent textures