I have a Content Template designed using block editor. It is assigned to my activities type (as defined by toolset), but assigned conditionally only for one taxonomy match (my activity category taxonomy).
When I try to add dynamic content to the content template, It doesn't recognize the post source should be an activity in the drop-down box. It lists Current Post instead of Current Activity. This means I can't access items in my custom field group to display dynamically. See attached picture for dynamic content and to see how content template usage is set.
The template has been saved and reloaded and I still see the same behavior. The behavior is consistent whether it is inline dynamic content or dynamic content assigned at the block level.
It is not very intuitive, but the preview post used when editing the template will need to match the conditions specified for using the template for the correct fields to be available as dynamic sources.
So if you use the template for some posts with a specific taxonomy term assigned, be sure to select a preview post that has that term assigned.