Vaults are gone to nirvana

#1

Game mode: [Online | Singleplayer]
Problem: [Crash | Bug | Performance | Misc]
Region: [Here]

[Free text]

Every day when we log in our vaults are gone without any attacks or so. There GONE!!

Steps on how to reproduce issue:
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#2

Were they on structures or just placed on the ground? If a vault is placed directly on the ground it has a maximum decay timer of 5 hours.

#3