There are two common causes:

• You're on a legacy template. Liquid tags only process in Liquid templates. Check your template type.
• Syntax issue — you're nesting Liquid inside the vary() array. Personalization and Liquid logic must be resolved inside assign statements before being passed to vary(). See Setting Up Content Variations for the correct pattern.

Every vary() tag in a template must have the same number of items. The error "All vary function calls must have the same number of items. Expected 2, found 3" means one tag has a different array length. Check each vary() tag and align them.

No. Duplicated templates start fresh — no weights, no history, no performance data transfers. The duplicate begins a new optimization cycle from equal distribution.

Removing content variations hides variant performance data from Mission Control. The underlying data is retained, but is no longer visible in the breakdown view. Export or record your results before removing content variations from an active template.

No. All variants stay active, but traffic distribution becomes heavily skewed. A leading variant can receive 60%+ of traffic while an underperformer drops to ~4%. The system keeps a thin exploration slice on every variant.

Send 1 is always equal distribution. From Send 2 onward, weights adjust based on engagement. For best results by campaign type:

• Recurring: Allow 3–5 sends before drawing conclusions. Avoid pausing and restarting, as this interrupts the optimization cycle.
• Intraday: Aim for a send window of at least 2–3 hours with meaningful volume in each 15-minute batch.
• Triggered: High-frequency flows optimize fastest. For lower-volume triggers, allow more time before expecting significant weight shifts.

Optimization is based on total engagement for the channel: email uses opens and clicks; SMS uses tracked link clicks; push uses opens.

Yes — they run on separate layers. STO controls timing, Content Decisioning controls content. See Monitoring Content Decisioning Performance for how they interact and when the combination works best.

Currently, vary() accepts plain text strings only. Content blocks, data connections, and images are on the roadmap. You can use Liquid personalization (e.g., customer.FIRST_NAME) but it must be built inside assign statements, not nested in the vary() array.

Up to 4 per vary() tag.

No. All vary() tags within a template are linked and must be 1:1. Combinatorial variations are planned for a future release.

Email, SMS, and push. SMS requires a tracked link in the message for optimization to work — without it, the system has no engagement signal to measure.

All — scheduled and triggered.