Question Box projection data wiped when selecting refleciton probe

I am trying to make a shader that gets box projected reflection from a reflection probe in URP.

if i compile my shader it works but as soon as i select the reflection probe it looks like the BoxMin, BoxMax and the ProbePosition just get wiped. it stays like this until i recompile my shader

Any help would be greatly apriciated!

Code (CSharp):

1. // Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
2.  
3. // Upgrade NOTE: replaced '_Object2World' with 'unity_ObjectToWorld'
4.  
5. Shader "Unlit/Djanco/BoxProjection"
6. {
7.     Properties
8.     {
9.         //_MainTex ("Texture", 2D) = "white" {}
10.         //_ReflPos ("Probe Position", float) = (0,0,0,0)
11.     }
12.     SubShader
13.     {
14.         Tags { "RenderType"="Opaque" }
15.         LOD 100
16.  
17.         Pass
18.         {
19.             CGPROGRAM
20.             #pragma vertex vert
21.             #pragma target 4.0
22.             #pragma fragment frag
23.             // make fog work
24.             #pragma multi_compile_fog
25.  
26.             #define UNITY_SPECCUBE_BLENDING
27.             #define UNITY_SPECCUBE_BOX_PROJECTION
28.             #define UNITY_ENABLE_REFLECTION_BUFFERS
29.             #define UNITY_SPECCUBE_BOX_PROJECTION
30.  
31.             #include "UnityCG.cginc"
32.  
33.             struct appdata
34.             {
35.                 float4 vertex : POSITION;
36.                 float2 uv : TEXCOORD0;
37.                 float3 normal : NORMAL;
38.             };
39.  
40.             struct v2f
41.             {
42.                 float2 uv : TEXCOORD0;
43.                 float4 vertex : SV_POSITION;
44.                 float3 viewDir : TEXCOORD3;
45.                 float4 worldPos : TEXCOORD4;
46.                 float3 normal : TEXCOORD5;
47.             };
48.  
49.             sampler2D _MainTex;
50.             float4 _MainTex_ST;
51.             float3 _ReflPos;
52.  
53.             v2f vert (appdata v)
54.             {
55.                 v2f o;
56.                 o.worldPos = mul (unity_ObjectToWorld, v.vertex);
57.                 o.vertex = UnityObjectToClipPos(v.vertex);
58.                 o.viewDir = WorldSpaceViewDir(o.worldPos);
59.                 o.uv = TRANSFORM_TEX(v.uv, _MainTex);
60.                 o.normal = v.normal;
61.                 return o;
62.             }
63.  
64.  
65.  
66.             float3 BoxProjection (float3 direction, float3 position, float3 cubemapPosition, float3 boxMin, float3 boxMax)
67.             {
68.                 float3 factors = ((direction > 0 ? boxMax : boxMin) - position) / direction;
69.                 float scalar = min(min(factors.x, factors.y), factors.z);
70.                 return direction * scalar + (position - cubemapPosition);
71.             }
72.  
73.  
74.             fixed4 frag (v2f i) : SV_Target
75.             {  
76.                 float3 worldNormal = mul( unity_ObjectToWorld, float4( i.normal, 0.0 ) ).xyz;
77.  
78.                 float4 worldPos = i.worldPos;
79.                 float3 WorldSpaceViewDirection = _WorldSpaceCameraPos.xyz - worldPos;
80.                 WorldSpaceViewDirection *= abs(worldNormal) * 2 - 1;
81.  
82.                 float3 boxMin = unity_SpecCube0_BoxMin;
83.                 float3 boxMax = unity_SpecCube0_BoxMax;
84.                 float3 probePos = unity_SpecCube0_ProbePosition;
85.  
86.                 float3 projection = BoxProjection(WorldSpaceViewDirection, worldPos, probePos, boxMin, boxMax);
87.  
88.                 half4 skyData = UNITY_SAMPLE_TEXCUBE_LOD(unity_SpecCube0, projection, float4(0,0,0,0));
89.  
90.                 return skyData;
91.             }
92.             ENDCG
93.         }
94.     }
95. }
96.  

 

Updating unity to LTS 2020 fixes this problem