Surface Shader works on Web, Mac, iOS but not Android

I'm just talking about running the game within Unity. When I switch platforms to Android, the surface shader I've written doesn't work. I wrote it to fallback to Diffuse, but it the object is just black.

What do I need to do to ensure that a surface shader will run on Android? I haven't actually tested it on a device at this point.

Here is the surface shader in question:

 Shader "Custom/Squared" {
     Properties {
         _MainTex ("Base (RGB)", 2D) = "white" {}
     }
     SubShader {
         Tags { "RenderType"="Opaque" }
         LOD 200
         
         CGPROGRAM
         #pragma surface surf SquaredLambert
 
         #pragma debug 
 
         sampler2D _MainTex;
 
          half4 LightingSquaredLambert (SurfaceOutput s, half3 lightDir, half atten) {
               half NdotL = saturate(dot (s.Normal, lightDir));
               half4 c;
               c.rgb = s.Albedo * _LightColor0.rgb * (NdotL * sqrt(atten) * 2);
               c.a = s.Alpha;
                return c;
         }
 
         struct Input {
             float2 uv_MainTex;
             float4 color : COLOR;
         };
 
         void surf (Input IN, inout SurfaceOutput o) {
             half4 c = tex2D (_MainTex, IN.uv_MainTex);
             o.Albedo = c.rgb;
             o.Alpha = c.a;
         }        
         
         ENDCG
     } 
     FallBack "Diffuse"
 }