Issue setting Sprite alphas

I'm assuming that I'm not accessing the sprite renderer properly or setting the alpha wrong, but I keep getting weird results with this where sprites become near black. Sometimes it works right, sometimes not. I stripped everything down and simplified this loop so the sprites should either be full alpha or 75% transparent, which most are, but some will just randomly show up super dark..

Code (CSharp):

1.  
2.         protected override void OnUpdate()
3.         {
4.             if (RecalcAlpha)
5.             {
6.                 RecalcAlpha = false;
7.                 Entities
8.                     .WithAll<CellComponent>()
9.                     .WithAll<Sprite2DRenderer>()
10.                     .ForEach((ref Sprite2DRenderer sr, ref CellComponent cellData) =>
11.                     {
12.                         var alpha = RandomExtra.OneIn(ref rand, 2) ? 0.25f : 1f;
13.                         sr.color.a = alpha;
14.                     });
15.             }
16.         }
17.  

Tons of stuff removed to make sure it's not some interaction with other parts of the map:

 

took those out and no effect:

Code (CSharp):

1.         protected override void OnUpdate()
2.         {
3.             if (RecalcAlpha)
4.             {
5.                 RecalcAlpha = false;
6.                 Entities.ForEach((ref Sprite2DRenderer sr, ref CellComponent cellData) =>
7.                     {
8.                         var alpha = RandomExtra.OneIn(ref rand, 2) ? 0.20f : 1f;
9.                         sr.color.a = alpha;
10.                     });
11.             }
12.         }
13.  

weirdly when i move the var alpha outside the loop, the effect never reproduces. which smells of some strange code gen issue?

Code (CSharp):

1.        protected override void OnUpdate()
2.         {
3.             if (RecalcAlpha)
4.             {
5.                 var alpha = RandomExtra.OneIn(ref rand, 2) ? 0.20f : 1f;
6.                 RecalcAlpha = false;
7.                 Entities.ForEach((ref Sprite2DRenderer sr, ref CellComponent cellData) =>
8.                     {
9.                         sr.color.a = alpha;
10.                     });
11.             }
12.         }
13.  

 

I find that lambda's don't allow me to use reference versions of exterior values. I have to do precalculation to a value type before feeding it into such lambdas. I'm surprised you're not getting a compilation error though...