When uploading a custom skin (either from MC launcher or minecraft.net) and selecting the "Slim" Alex model, the skin gets updated, but it will appear on a Steve model when in-game, along with black bars on the arms. The skin is labelled as "slim" when viewing it in MC launcher and on minecraft.net however.

I've checked with both single-player and multiplayer modes, they both have the same issue. In multiplayer, I've noticed that players with default Alex models (with no custom skin) do get rendered properly and have the right Alex model.

Others seem to be having the same problem in the past 24 hours. External links:

• https://www.minecraftforum.net/forums/support/java-edition-support/3017159-skin-model-not-working
• https://hypixel.net/threads/steve-hypixel-skin-bug.2815342/
• https://hypixel.net/threads/skin-problem.2814628/#post-19399893