When waterlogging stairs, there is a visual glitch. Some details:

• The visual bug is a flickers, as though it clips in and out of water.
• It does not appear on every stair.
• The bug seems to be more present when the stair is facing either north or south.
• The bug seems to be less present when the stair is facing either east or west.
• As the previous two statements, flowing water textures don't seem to connect right when they are flowing either north or south.
• Again, flowing water textures do connect when flowing either east or west.
• Tested this in both an area affected by commands and areas unaffected by commands, this provided no change in the results.

As a sidenote, if the stair is a corner, or the water flows as a corner, it never has this issue.

Tested with texture packs and pure vanilla, this provided no change in the results.

Regardless of orientation, the bug does not always affect north/south facing stairs, just for the most part.

I have not had this visual glitch at all with east/west facing stairs.

Although it has no impact on gameplay, it does make a lot of builds look horrible.