In single-player or multiplayer [any game version] skins do not show up on myself or other players. Players appear as either Steve or Alex.

My Minecraft launcher will not save skins [Images attached].

I have uploaded skins to minecraft.net however, they still do not appear in-game. My character appears as Steve. 

This happens in game version 1.12.2 and 1.16.5 [I only play these versions] but I assume it affects all versions.

I have tried restarting the game, it did not work. I tried restarting my computer, it did not work. I tried reinstalling the game, it did not work. Finally, I tried reinstalling the launcher, it did not work. [this also happens with and without mods]

I need help.