Stair, Slab, Soulsand, and Path Block F3 Lighting Glitch

I was on Minecraft Realms with my brother and we were building something with some stair blocks. I left to go work on something else and he stated that there was a zombie in the other room. I had been messing around with the F3 lighting and I was confused because the area was well lit. I went into F3 and scoped out the area and found that the stair blocks that we had placed were reading a light level of 0. We checked all of the stairs and they all read that they were at 0, so I had the idea to check it out in Single Player. I made a new world and dug a small pit and placed down another stair block and checked F3 again. I had the same problem in Single Player.

It would be most appreciated if this could be fixed. Thank you!