Making a custom Fatigued icon goes awry

[Newbiespud]

TL;DR: Invulnerable/Personality argument images don't fill up the frame currently, and .png images to textures get really pixel-crunched when downscaling, especially at lower resolutions.

Now that Fatigued has individual icons for each character, I thought I should see about making one for Arint! And I'm... most of the way there.

Here's the image I'm trying to use (drawn by @onetinybee):

I'm using this code to override Fatigued's OnInit and append my own check:

local old_fatigued = Content.GetNegotiationModifier("FATIGUED")
local old_fatigued_init = old_fatigued.OnInit

function old_fatigued.OnInit(self, source)
      old_fatigued_init(self, source)
      if self.negotiator.agent:GetContentID() == "PC_ARINT" then
            self.icon = engine.asset.Texture( "ARINTMOD:textures/Arint_Fatigue.png", true )
      end
end

Note that simply self.icon = "ARINTMOD:textures/Arint_Fatigue.png" causes a crash when Fatigue is added. (bad argument #2 to 'SetTexture' (Not a valid texture asset))

This is what this setup currently looks like in-game:

It's a little hard to tell, but there's a gap, a sliver of transparency, on the top and bottom of the frame for Fatigued. It's not filling the frame.

It's a square image, 256x256, and it still turns out this way even with an upscaled 512x512 version. When I use this image for another modifier's icon, like Arint's core argument, it looks much better:

Here it's filling the frame and not as roughly downscaled.

So I can only assume it's possibly the reassignment of the icon and/or the engine.asset.Texture() call that's messing things up? I'm a bit stumped.

EDIT: Wait, every Personality/Invulnerable argument seems to have this framing issue. The roughness of the downscaling is still very noticeable, though, especially at lower windowed resolutions.