Note: If you are using Google Tag Assistant to verify conversion tracking and remarketing tags that were implemented using gtag.js, you will see an additional entry titled "Google tag (gtag.js)" in addition to your AdWords conversion tracking or remarketing tags.
Account ID in gtag.js URL is invalid or missing
The Google tag snippet loads gtag.js using the following path: /gtag/js?id=PRODUCT_ACCOUNT_ID, where PRODUCT_ACCOUNT_ID is an ID for the product and account (or property) from which the Google tag snippet was generated (or should be associated).
Failing to properly set this ID should not directly affect the data received by your accounts, but may affect future functionality.
Solution: Ensure that the ID in your gtag.js code is correct.
gtag() commands are found without the Google tag snippet
gtag() commands have been detected without the Google tag snippet present.
Without the proper Google tag installed, calls to gtag() won't work.
Solution: Ensure that the Google tag is properly installed on the page.