In some occasions there is a 4 sections cube hole in tha mansion, where there also is no floor generated
See pictures for more details!
Where I found this (16w39b):
Seed: 3888442674554197564
Location: -25121 | 80 | 17617
Environment
Windows 10 Anniversary Update
Java 1.8.0_101
PC: - i7 5820k @ 4Ghz - GTX980 (driver: 372.90) - 16GB RAM
Attachments
Comments
4
migrated
Jens Bergensten
Community Consensus
Minecraft 16w39a, Minecraft 16w39b, Minecraft 16w39c, Minecraft 16w40a, Minecraft 16w41a
Minecraft 16w43a
Retrieved
I can confirm this, and that it was also present in 16w39a.