3d Text Shader receives shadow only on editor

I've made after some work this shader that receives shadows (for 3d text). In the editor it works well but when I build and run the stand-alone player it doesn't do the cut-alpha thing anymore and the text becomes a square of same color. I'm using the player for the Windows PC version and I can't figure out what's wrong.

Does anyone know what could be causing this?

On Editor:

On Player:

This is my shader (it's a modified version from Unity 3d manual):

Edit: Please ignore that there are two lighting functions, they are there because of the tests I was running before reaching this result.

 Shader "Example/3D Font Shader" {
     Properties{
         //_MainTex("Main Texture", 2D) = "white" {}
         _FontTex("Font Texture", 2D) = "white" {}
         //_Color("Text Color", Color) = (1,1,1,1)
     }
     SubShader
     {
         CGPROGRAM
         //sampler2D _MainTex;
         sampler2D _FontTex;
         half4 _Color;
         #pragma surface surf SimpleLambert alphatest:_Cutoff        
 
         half4 LightingWrapLambert(SurfaceOutput s, half3 lightDir, half atten) {
             half NdotL = dot(s.Normal, lightDir);
             half diff = NdotL * 0.5 + 0.5;
             half4 c;
             c.rgb = s.Albedo * _LightColor0.rgb * (diff * atten);
             c.a = s.Alpha;
             return c;
         }
 
         half4 LightingSimpleLambert(SurfaceOutput s, half3 lightDir, half atten) {
             half NdotL = dot(s.Normal, lightDir);
             half4 c;
             c.rgb = s.Albedo * _LightColor0.rgb * ((NdotL + 1) * atten);
             c.a = s.Alpha;
             return c;
         }
 
         struct Input
         {
             //float2 uv_MainTex;
             float2 uv_FontTex;
             half4 color : Color;
         };
         void surf(Input IN, inout SurfaceOutput o) {
             half alpha = tex2D(_FontTex, IN.uv_FontTex).a;
             o.Alpha = alpha;
             //o.Albedo = tex2D(_MainTex, IN.uv_MainTex).rgb;            
             o.Albedo = IN.color.rgb;
         }
         ENDCG        
     }
     Fallback "Transparent/Cutout/Diffuse"
 }

• UPDATE -- After I found a solution I posted below for reference. Apparently this is very difficult to achieve so I hope it helps more people who wants 3d Text receiving shadows in unity. So glad I found this, the power of rubber duck debugging! :-D