Hi - as a brand-new user of Affinity, I installed it (purchased from Apple App Store) on MacOS Mojave 10.14.2, and help is non-functional.
When I search for a topic in the Help menu inside Affinity, the help window shows up blank. If I search again using the same string in the Search box inside Help, a list of topic headings actually show up in the Help window. But clicking on any of those topic headings once again results in a blank help window. So, I can see the topics exist, but cannot display any of the actual help content.
It looks like the promise of MacOS 10.14.2 fixing this issue has not been realized.