Player skulls aren't updating with skin changes on my end,

At first when I changed my skin, the player skulls I spawned would only change when loading certain skins on my end but now they aren't changing at all. However, at least one player on a realms server I play on apparently sees the skulls as matching my current skin. Attached are the skin I used for the skull, (gokaichristmas.png) and my current skin (MetropoliceAltEyes.png), which previously worked with the skulls and one that did not (Wing Ace.png).