Not all tags are fired in Google Tag Manager preview mode

Have you encountered Tags that do not fire when testing your setup? This support article outlines common solutions and the steps you can take to address these issues. This support article will first guide you through common scenarios that may prevent a tag from firing. Following that, we will delve into specific situations that require a more targeted approach to troubleshooting. 

For a detailed guide on testing your setup, please refer to our blog: Testing Server Side Tracking Setup

General Reasons Why a Tag Doesn't Fire

Here are general reasons why a tag might not be firing within Google Tag Manager:

Incorrect Trigger

A tag not firing often comes down to an issue with the trigger. Ensure all conditions of your trigger are correctly set. A single misconfigured condition can prevent a tag from firing.

Blocking Trigger is Added

Blocking triggers prevent a tag from firing under specific conditions. If a blocking trigger is active, it will override other triggers, stopping the tag from firing.

Misunderstood Functionality of Blocking Triggers

Blocking triggers only work against firing triggers that use the same events. If the event types don't match, the blocking trigger won't prevent the tag from firing.

Tag Sequencing

Sometimes, tags are set to fire in sequence. If a tag is part of a sequence, it might not fire due to its position in the sequence, not because its trigger conditions were met.

Tag Firing Options

A tag set to fire "Once per page" will not fire multiple times, even if its trigger conditions are met repeatedly on the same page.

Tag Firing Schedule

Tags can be scheduled to only fire within a specific timeframe. If the schedule doesn't align with your testing time, the tag won't fire.

Fire a Tag Only in Published Containers

Some tags are configured to only fire in live, published containers. These won't fire in preview and debug modes or in unpublished containers.

gtm.blocklist and gtm.allowlist

Developers can restrict certain types of tags from firing. If your tag falls into a blocked category, it won't fire.

Specific Situations

Google Analytics 4 Configuration Tag Not Firing

Check in preview mode if the GA4 Tag is firing. If it fires in the web container but not in the server container, check if the Measurement ID (Web Container) and the Tag ID (Server Container) in the GA4 Configuration tags match.

Understanding the nuances of why a tag might not be firing is crucial for diagnosing and fixing the issue.

Follow the steps outlined above to troubleshoot and resolve common tag firing issues in Google Tag Manager. Remember, detailed testing and verification are key to ensuring that your tracking setup works as intended.

Google Tag manager not firing Tags _TAGGRS

Google Tag Manager Debug: Page Views Detected but No (E-commerce) Eventsnot-all-events-got-triggerd-gtm-preview-mode

In situations where Google Tag Manager's debug mode shows page views but fails to register e-commerce events, the issue often lies in the alignment between the Google Tag's Measurement ID and the e-commerce configuration. It's crucial to ensure that the Measurement ID used in your Google Tag setup matches exactly with the one configured for e-commerce tracking. Discrepancies between these IDs can lead to page views being tracked correctly while e-commerce events are missed. Double-check these configurations to ensure consistency and correct tracking of all desired actions on your site.

Google Tag manager configuration tag settings

Also make sure you don't have any duplicate Tracking Script in Code. In some cases, we see that the Google Tag Manager script is loaded in multiple ways in the code, often through manual placement + via a plugin. This can disrupt tracking in some cases. Therefore, always check if there is a tracking code (per container) in the code.

In the screenshot below, you can see that tracking is sent to multiple sources. Ideally, you want only server side domains to be listed here where you send the data. Otherwise, events can be hijacked by the others.