Wooden Boxes & Foundation Blocks Disappeared

Game mode: [Online PvE - 2501]
Problem: [Bug]
Region: [Americas]

I placed about 15 to 20 foundations blocks in the water under the “tunnel” in the “canal” just west of the Boundary Spillway. I also placed three wooden boxes (on ground), a campfire (on ground) and a fishtrap.

Before the 31-May-2018 Hotfix, the 3 wooden boxes disappeared.
After the 31-May-2018 Hotfix, all of the foundation blocks disappeared.

The only things left is the campfire and the fishtrap.

It did not decay because I only placed them two or three days prior to them disappearing.
They cannot be destroyed by players.
There was no purge.

There is nothing in the event log showing what happened.

I do not know if this can be reproduced as I am not wasting time trying to build in that server again. I will just play as a nomad without a home.

Steps on how to reproduce issue: