Why Conversions Stopped While Spend Continued

The short version

When spend continues and conversions go to zero, there are two possibilities, and they are not equally likely:

The conversions are not happening. Something broke in the funnel or the traffic changed.
The conversions are happening and not being reported. Tracking broke.

The second is more common than the first, and the two look identical in the ad platform. Confirm which before changing a single campaign setting.

Check reporting before performance

One question settles it: is your own source of truth still recording sales?

Check the backend, the CRM, the payment processor — whatever records revenue independently of the ad platform. If orders are still arriving at a normal rate, the campaign is fine and your measurement is broken. Everything else in this post is then irrelevant.

This check takes a minute and prevents the expensive mistake, which is pausing working campaigns because a tag stopped firing.

If tracking broke

Common causes, roughly in order of frequency:

A site deploy removed or altered the tag.
A consent or privacy tool changed behavior and now blocks the event.
The event name or parameters changed, so the platform no longer recognizes it.
A domain or subdomain change broke the tracking chain.
Server-side event forwarding stopped.
Checkout moved to a third-party flow that the tag does not cover.

The timing usually gives it away. Conversions going to zero on a specific day, rather than declining, points at a change. Ask what shipped that day.

If conversions genuinely stopped

Work down the funnel from where the ad hands off.

The landing page. Is it loading, and loading fast? Did it change? A broken or slowed page produces exactly this pattern.

The purchase flow. Payment failures, an out-of-stock product, a broken form, a coupon that expired, a required field that started rejecting valid input.

The traffic. Did the audience shift? Automated targeting expanding into unqualified people produces clicks that never convert. Check whether CTR held while conversion rate collapsed — that pattern means people are still clicking and no longer buying.

Attribution window. If the optimization event has a long delay and the window changed, conversions may be arriving but landing outside the reported period.

The most expensive mistake

Pausing campaigns while investigating.

If the cause was tracking, you have stopped working campaigns and reset their learning for nothing. If the cause was a broken checkout, pausing does not fix the checkout.

The correct sequence is: verify against your own revenue source, then fix the actual cause, then decide about campaigns. Pausing is a last resort, not a first response.

Practical rule

Before touching any campaign, check whether your backend still shows orders. Tracking failures and performance collapses look identical in the ad platform and identical to each other on a chart, and only your own revenue data separates them.