Check for not processed or explicitly ignored functions instead of just ignored, since ignored also checks for IsGenerated which is incorrect in this instance (eg. we dont want to generate wrapper methods for getters, but we still need their internal declaration for properties).

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -1719,7 +1719,8 @@ namespace CppSharp.Generators.CSharp
 
         public void GenerateInternalFunction(Function function)
         {
-            if(function.Ignore) return;
+            if (!function.IsProcessed || function.ExplicityIgnored)
+                return;
 
             GenerateDeclarationCommon(function);
             WriteLine("[SuppressUnmanagedCodeSecurity]");