This was discovered on a personal creative server with just command blocks running to provide regen, saturation, and delete dropped items from the world. Not sure why exactly these commands would affect the behavior of scaffolding, but they did. This bug does not occur on a regular singleplayer world, so this is either a multiplayer bug or a command block bug, as this server was hosted by Aternos.

Here is a link to a video I recorded of this issue:

https://www.youtube.com/watch?v=TJcIqOq5K6U