I do need a log with the game running. Otherwise I can't properly tell what the issue with the pink box is, the skin shader is irrelevant and merely an artifact of using 1.0.

Thank you for getting back to me. So I can safely ignore the 'skin shader' thing?

Starting a new colony and adding Avian pawns has shown that the Dodo and Cassowary varieties seem to have the pink box problem. It looks like the heads and clothes are being drawn but not the bodies.

Log: https://gist.github.com/55bd40975288a8d3cef3570fa5dc6ebb

To test further, I removed the Avian race mod and added int eh LoTR Elves and they seem to be fine, so it looks like the issue with the pink boxes is something to do with the Avians mod.

Log with Elves here: https://gist.github.com/83191cbcc2d68ced209af57036bf6bbf

Copy of Dodo error here (pops up when the colonist selection loads. There is no portrait shown for them either)

Failed to find any texture while constructing Multi(initPath=Things/Dodo/Body/Naked_Fat, color=RGBA(0.435, 0.306, 0.159, 1.000), colorTwo=RGBA(0.435, 0.306, 0.159, 1.000)). Filenames have changed; if you are converting an old mod, recommend renaming textures from *_back to *_north, *_side to *_east, and *_front to *_south.
Verse.Log:Error(String, Boolean)
Verse.Graphic_Multi:Init(GraphicRequest)
Verse.GraphicDatabase:GetInner(GraphicRequest)
Verse.GraphicDatabase:Get(String, Shader, Vector2, Color, Color)
AlienRace.AlienPartGenerator:GetNakedGraphic(BodyTypeDef, Shader, Color, Color, String, String)
AlienRace.HarmonyPatches:ResolveAllGraphicsPrefix(PawnGraphicSet)
Verse.PawnGraphicSet:ResolveAllGraphics_Patch1(Object)
Verse.PawnRenderer:RenderPawnInternal_Patch1(Object, Vector3, Single, Boolean, Rot4, Rot4, RotDrawMode, Boolean, Boolean)
Verse.PawnRenderer:RenderPortrait()
RimWorld.PortraitRenderer:OnPostRender()
UnityEngine.Camera:Render()
RimWorld.PortraitRenderer:RenderPortrait(Pawn, RenderTexture, Vector3, Single)
RimWorld.PortraitsCache:RenderPortrait(Pawn, RenderTexture, Vector3, Single)
RimWorld.PortraitsCache:Get(Pawn, Vector2, Vector3, Single)
RimWorld.Page_ConfigureStartingPawns:DrawPawnList(Rect)
RimWorld.Page_ConfigureStartingPawns:DoWindowContents_Patch1(Object, Rect)
Verse.<WindowOnGUI>c__AnonStorey0:<>m__0(Int32)
UnityEngine.GUI:CallWindowDelegate(WindowFunction, Int32, Int32, GUISkin, Int32, Single, Single, GUIStyle)


( Possibly a slightly easier to read log here: https://gist.github.com/c615afc50048dba21b67738442746148 )

Can you give me any idea of what this is about? I know it relates to textures somehow but not what the problem is or how to fix it.

I appreciate that it looks like it's actually not this mod at all and I appreciate your help so far.

yeah misconfiguration and/or missing textures in the respective mods. The mod author just didn't provide textures for all bodytypes.