Not sure if this is a bug, but sometimes obsidian and crying obsidian blocks do not face always the same direction. Sometimes it looks like if the block where in a horizontal orientation and sometimes it looks like if they were facing in a vertical direction.

I know that this issue does not actually affect the game, but as far as I know, obsidian is not a block that can change its orientation. The real problem, is that it affects the aesthetics of the game when building portals. (I tried to put the block in different direction, but it did not work).

I attached an image for you to visualize the issue.