Cutout Shader with Vertex Color (always black)

Hi, I created an extension of the cutout diffuse shader. I wanted to add custom vertex color, but it always turns out black. (It did work without a cutout shader but just a diffuse shader)

My shader:

 Shader "Transparent/Cutout/Diffuse Color" {
     Properties {
         _Color ("Main Color", Color) = (1,1,1,1)
         _MainTex ("Base (RGB) Trans (A)", 2D) = "white" {}
         _Cutoff ("Alpha cutoff", Range(0,1)) = 0.5
         _vertStrength("Color Strength", Range(0.0, 2.0)) = 1.0
     }
     SubShader {
         Tags { "Queue"="AlphaTest" "IgnoreProjector"="True" "RenderType"="TransparentCutout" }
         
         CGPROGRAM
         #pragma surface surf Lambert alphatest:_Cutoff
 
         sampler2D _MainTex;
         float _vertStrength;
         fixed4 _Color;
 
         struct Input {
             float2 uv_MainTex;
             float3 vertColors;
         };
         
         void vert (inout appdata_full v, out Input o) {
             o.vertColors = v.color.rgb;
             o.uv_MainTex = v.texcoord;
         }
 
         void surf (Input IN, inout SurfaceOutput o) {
             half4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
             c.rgb = lerp(c.rgb, c.rgb * IN.vertColors.rgb, _vertStrength);
             
             o.Albedo = c.rgb;
             o.Alpha = c.a;
         }
         ENDCG
     } 
     FallBack "Transparent/Cutout/Diffuse"
 }

Also, in my mesh I add Color32 to the colors32 list.

I made sure it are all valid values, and not just 0