What did you see in the flush agent (in author) log? Can you post that log along with the dispatcher's log?

I see, sorry about the confusion, it looks like the web optimizer needs to be enabled somehow for that dataType used in the content fragment model in order to enable that property in the ImageRef, but as you pointed out, there seems to be some step missing, I guess you verified your instances can ac...

Is this AEMaaCS? if so, can you try to get the full log? You can learn here how to download it: https://experienceleague.adobe.com/docs/experience-manager-cloud-service/content/implementing/using-cloud-manager/manage-logs.html?lang=en

The error stack trace should uncover where the null is initialed passed to the EmailNotificationService, can you check or post the complete stack trace and not only the initial lines? 

The error is clear the _dynamicUrl field does not exist in the imageRef object, when I look at the references available, I just see this, is it possible you mistaken the name of what you are looking for? Also you can use the "Documentation Explorer" in the right section of the ghrapql UI(http://loca...

Additionally, check if you don't have ACL issues, perhaps the folder is not allowed by an anonymous user, did you try once logged in to the publish instance?

The SP (service pack) are updates applied on your AEM instance, what you are running through the terminal is the code that will be deployed into your AEM instance, these are different things. Download the SP from here: https://experience.adobe.com/#/downloads/content/software-distribution/en/aem.htm...

What you are seeing in red is dependencies that need to be installed, which version of AEM are you running on? According to the official wknd repo, you need at least SP13, https://github.com/adobe/aem-guides-wknd and also please install the acs commons package from here: https://github.com/Adobe-Con...

Your "WKND Site Core" bundle is not active but it shows in the "installed" state. Click the "play" button to activate it. That should fix it

Can you check if the bundles are active? Did you find any ERROR statements in the log? I would recommend restarting the instance and checking once more: 1) the bundles, and 2) the logs. Then post back what are you seeing in the logs.