Missing analytics.js script
Re: Missing analytics.js script
It is because your Google Analytics snippet is wrapped with 'timeout' function that is set to trigger in 20 seconds:
In this case, Tag Assistant finds the snippet but since the snippet is not executed, analytics.js is not being loaded and there is no GA pageview request. This is why you are receiving this error. If you are using a wordpress plugin for GA, please check that plugin's settings. Alternatively, you can try to use another wordpress plugin or you can put your GA snippet into your header template.
I hope this helps.