Voxel shadows Bug

Hello guys, I want to ask you to help me with one problem in my game, which is made entirely of voxels, when the model is not illuminated by the sun, that is, there is a bug or something that makes the entire back view of the object completely without shadows, as if I turned them off, although this is not so, and when the sun’s light falls on the model, the shadows are perfectly drawn, I even turned the shadows off and back on and nothing changes on the back side of the model (not on the side of the sun) here are some photos so you understand what I mean. And by the way, I specifically put a NON-VOXEL model and there was no such problem, the problem is apparently in the voxel model. Sorry for the mistakes, I don’t know English well
Enough


This is from the sun lights side and it’s looks a lot better.

And here is shadows on/off photos

And this is from the back, and here’s the problem, looks like shadows turned off but it’s not…