If I select one of my reference images here, AND I’m in Material Preview, the mesh is not visible. In solid mode, it is visible. (And it was working on my other, desk machine…)
What am I missing here? I know it’s going to be embarrassingly simple…
OldGuy_Model_2.blend (682.6 KB)
We’ve all been there 
In the materials settings, you have set the Blendmode to “Alpha Clip”. That means that alle Alpha Values < 0.5 will be completely invisible, while Values > 0.5 will be opaque. Since you set it to exactly 0.5 in the Shader, it’s invisible. To fix this, set the Blendmode to “Alpha Blend”.
I would recommend to just use Solid Mode with X-Ray for this purpose though.
Many thanks: .5 vs .51, arghghghghghghghgh!!! LOL 
