If a PMax campaign is spending but not converting, it is rarely a “glitch.” In 2026, it almost always boils down to one of these four pillars: Tracking, Learning Phase, Signal Quality, or Placement Waste.

1. The “Broken Compass” (Conversion Tracking)

PMax optimizes toward the conversion data it receives.If tracking is broken, the AI is “flying blind.”

• The Check: Go to Goals > Conversions > Summary. Is your primary conversion status action showing “Active“? 

• The 2026 Issue: Ensure you aren’t using “soft” conversions (like Page Views or 30-second visits) as Primary actions. If you do, PMax will spend your entire budget finding people who click around but never buy.

• The Fix: Set only the “Bottom of Funnel” action (Purchase/Lead) to Primary. Set everything else to Secondary.

2. The “Aggressive Student” (Learning Phase)

When you first launch a PMax campaign, the AI goes into “Exploration Mode.” It bids high to test different audiences and placements.

• The Rule of Thumb: In 2026, PMax requires 2–4 weeks to stabilise.

• The Spending Spike: It is normal to see a 2x-3x spike in Cost Per Click (CPC) during the first 7 days as the algo probes for the best traffic.

• The Fix: Do not make changes. Every time you change a budget or a headline during the first 14 days, you reset the learning clock.

3. The “Garbage In, Garbage Out” (Audience Signals)

If your Audience Signals are too broad or outdated, Google might be showing your ads to the wrong people.

• The Check: Look at your Search Insights. Are the categories relevant? If you see “Free” or “Tutorial” searches for a luxury product, your signals are off.

• The Fix: Upload a Customer Match List (first-party data) of your actual past buyers.This is the strongest signal you can give the AI in 2026 to find similar people.

4. The “Placement Leak” (Display & Video Waste)

PMax serves across Search, Shopping, YouTube, Display, and Discovery. Often, the spend “leaks” into low-intent Display placements (like mobile games or apps).

• The Check: Use the “Placements” report (under Insights and Reports) to see where your ads are appearing.

• The Fix: If you see massive spend on “Mobile App” placements with zero conversions, use Account-Level Suitability Settings to exclude “All Apps” or specific sensitive categories.

Quick-Fix Checklist

A budget that is too low (e.g., less than 3x your target CPA) will cause the campaign to “thrash.” The AI needs enough budget to fail a few times before it finds the winner.