I was building with quartz, and found an annoying bug with quartz stairs. If you place outside corner stairs, they will have holes if placed in the correct direction. This doesn't seem to be the case with other stairs.

Steps to Reproduce:
1. Place two (2) quartz stairs in the same direction, as long as it is a negative direction.
2. Place another stair in the other negative direction, so you make a corner stair.
3. Place a solid block by the corner stair. You may need to try both places, but eventually, you will get a hole.