Autosave ignores settings and rolls back/deletes save progress

My sister turned the autosave feature completely off, but the game is ignoring the setting and forcing an autosave anyway. Because of this, her game completely rolled back today. She spent all of yesterday building a brand new house and moving her Sims into it, but when she logged in today, the house was entirely gone and her Sims were forcefully moved back to their old lot. Please fix this bug where autosave stays on and overwrites manual progress!