How does a shelf decay without the wall it is on not decaying?

Game mode: Online official
Type of issue: Bug
Server type: PvE
Region: America
Server: Official server #1510 PvE -
Mods?: No
Edition: Steam

Bug Description:

This is obviously a bug, something must have changed for shelves since the last patch. However, what puzzles me is that the shelf is decayed somewhere but I don’t know where, and a shelf is always on the wall, so why don’t I see a wall or foundation decayed in my logs?

Travelled around until I got close enough to see the same log at short range. No new work has been done there recently at all, the building hasn’t been touched in months.

Steps to Reproduce:

  1. Log in and check event logs since the last patch for maximum distance.