This bug also affects minecraft:redstone_torch & minecraft:redstone_lamp
Light sources, such as minecraft:torch will refuse to light blocks inside other chunks that should normally be lit/unlit, or it is slow to do so, and may require walking into the chunk or updating it by placing/destroying a block.

Works with every graphics configuration I have tested (Toggling VBOs, Fast/Fancy Graphics, Smooth/Non-smooth lighting), affects 1.12.2 and the latest snapshot as of writing (18w03b)