Solid blocks do not block light

[MaxLegend]

After I created the block and tile entity for my mod, I turned on the luminosity in different colors using this library. Unfortunately, for some reason, if you close the light source with solid blocks on all sides, it still shines brightly through the blocks. I thought for a long time, but never came up with how to solve this problem. I will be glad to help.
If this error cannot be fixed, nobody needs the library at all. This is a serious graphic error, I believe.
I am using minecraft version 1.12.2