SDK ver 3.8.1-beta.1
When setting platform overrides, which avatar you have selected when pressing build & publish still matters and it attempts to build & publish the avatar you have selected instead of what you specified in the platform overrides. I consider this to be a bug as the user already went out of their way to set a platform override, so I think that should take precedence.
An easy way to get this is to be on the android build platform and have your PC avatar as the selected avatar, obviously with your android version set in the platform overrides, and then build and publish with just the android platform set as the build target. The build will fail with avatar validation failed.