When I was digging down to mine, just digging in a 1 block wide staircase down, I tried to place a torch and it wouldn't place. I was directly next to the block I was trying to place a torch on. Then I tried moving around to different blocks and trying to place the torch but it wouldn't work. I could place a torch on any of the other blocks though.

I tried to replicate the issue and it seems that as long as you aren't directly to the left/right of the block you're trying to place a torch on it will let you, but once you do that it won't, and not only that the block will glitch and now it won't let you place a torch there no matter where you are. I'm unsure if this is still an issue in later versions, since I only play on 1.12.2

actually, it seems that I can't place torches anytime I'm directly next to the block