Packaging for Mac: Can't find asset Warning

Development Platform & Builds
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1

Hi

I am trying to package Unreal 4.12.3 a project for Mac and get the following log Warning:


 LogLinker:Warning: Can't find file '/Game/Architecture/SM_Floor_400x400'
 LogLinker:Warning: Can't find file '/Game/Architecture/SM_Floor_400x400'
 LogUObjectGlobals:Warning: Failed to find object 'Object /Game/Architecture/SM_Floor_400x400.SM_Floor_400x400'

This is an asset that I think was in an earlier iteration of my project but is no longer anywhere in the existing version and is nowhere in the Content.

Can anyone help by explaining why a reference such as this persists and how to remove it?

Thanks!