normal looks correct in direct light but reversed in the shadow on a terrain in 2018.4

you can see that in the realtime shadow the bumps look like dimples.
How can I fix that?
Note: it's on a terrain

Code (CSharp):

1. Shader "Ground Shader With Bliss - No Vertex Color" {
2.  
3.     Properties
4.     {
5.         _Color ("Main Color", Color) = (1,1,1,1)
6.         _MainTex ("Base (RGB)", 2D) = "white" {}
7.         _BlissTexVeryBad ("Very Bad Bliss", 2D) = "red" {}
8.         _BlissTexNeutral ("Neutral Bliss", 2D) = "white" {}
9.         _BlissTexVeryGood ("Very Good Bliss", 2D) = "green" {}
10.         _OutlineColor ("Outline Color", Color) = (0,0,0,1)
11.         _Outline ("Outline width", float) = .005
12.         _BlissBadNrm ("Bad Bliss Normal", 2D) = "red" {}
13.         _BlissNeutralNrm ("Neutral Bliss Normal", 2D) = "white" {}
14.         _BlissGoodNrm ("Good Bliss Normal", 2D) = "green" {}
15.  
16.     }
17.    
18.      // for desktop ------------
19.     SubShader
20.     {
21.         Tags { "RenderType"="Opaque" }
22.         LOD 900
23.        
24.         CGPROGRAM  
25.         #pragma surface surf Lambert halfasview vertex:vert addshadow fullforwardshadows
26.         #pragma target 3.0
27.  
28.         struct Input
29.         {
30.             half2 uv_BlissTexVeryBad;
31.             float3 worldPos;
32.         };
33.        
34.         void vert (inout appdata_full v, out Input o) {
35.             UNITY_INITIALIZE_OUTPUT(Input,o);
36.           }  
37.      
38.           sampler2D _BlissMap;
39.         sampler2D _BlissTexNeutral;
40.         sampler2D _BlissTexVeryBad;
41.         sampler2D _BlissTexVeryGood;
42.         fixed _BlissMapSize;
43.            sampler2D _BlissBadNrm, _BlissNeutralNrm, _BlissGoodNrm ;
44.              
45.         float3 blend_udn(float4 n1, float4 n2)
46.         {
47.             float3 c = float3(2, 1, 0);
48.             float3 r;
49.             r = n2*c.yyz + n1.xyz;
50.             r =  r*c.xxx -  c.xxy;
51.             return normalize(r);
52.         }
53.              
54.         void surf (Input IN, inout SurfaceOutput o)
55.         {  
56.             // bliss
57.             fixed2 w = half2(_BlissMapSize*.5 + IN.worldPos.x, _BlissMapSize*.5 + IN.worldPos.z);
58.             fixed2 pos = half2(w[0]/_BlissMapSize, w[1]/_BlissMapSize);          
59.             // take bliss value, add texture based on it
60.             fixed bliss = tex2D(_BlissMap,pos).a;
61.             half4 c1 = tex2D(_BlissTexVeryBad, IN.uv_BlissTexVeryBad);              
62.             fixed a1 = max(1 - bliss*2, 0);
63.             // NEGATIVE BLISS EFFECT
64.             //          comment both for just blended     - 1    
65.             fixed threshold = 1-c1.a;
66.             a1 = max(step(threshold, a1), min(a1/threshold, 1)); // threshold, blended mk 2- 4
67.             half4 c = c1*a1;                      
68.             c1 = tex2D(_BlissTexVeryGood, IN.uv_BlissTexVeryBad);          
69.             fixed a5 = max(bliss*2-1,0);
70.             // POSITIVE BLISS EFFECT
71.             //          comment both for just blended  - 1        
72.             threshold = 1-c1.a;
73.             a5 = max(step(threshold, a5), min(a5/threshold, 1)); // threshold, blended mk 2- 4
74.             c += c1*a5;
75.             c1=tex2D(_BlissTexNeutral, IN.uv_BlissTexVeryBad);
76.             fixed a3 = max(1-(a1+a5),0);          
77.             c += c1*a3;
78.             //total
79.             o.Albedo = c.rgb*1;
80.             o.Emission += c.a *c.rgb;
81.             half4 cn;
82.             //cn = tex2D (_BlissBadNrm, IN.uv_BlissTexVeryBad) * a1;
83.             //cn += tex2D (_BlissGoodNrm, IN.uv_BlissTexVeryBad) * a5;
84.             //cn += tex2D (_BlissNeutralNrm, IN.uv_BlissTexVeryBad) * a3;
85.             cn = tex2D (_BlissGoodNrm, IN.uv_BlissTexVeryBad);
86.             o.Normal = UnpackNormal (cn);
87.         }
88.    
89.         ENDCG
90.           UsePass "Toon/Basic Outline/OUTLINE"
91.     }

 

this inversion only happens if the terrain is baked, if i clear it it will suddenly work, this inversion also happens if i set the progressive baker to directional