After updating to KSP v1.6, Kerbal helmet visors appeared as bright pink due to a bad shaders file in TRR (GameData\TextureReplacerReplaced\Shaders). I uninstalled TRR and installed the newest version of TextureReplacer which fixed the issue. I didn't change or update anything else for Spectra and it seems to be working perfectly!
I will keep my eye out for an update to Scatterer but so far so good.