Data Layer Variable Not Showing in GA4

We’ve set up the GTM4WP plugin to push authors and categories for posts to Google’s data layer variables. Upon checking GTM in debug mode, the variables show correctly, however, the report that we have set up in GA4 only seems to correctly show post authors. Post categories are displaying as [object Object].

I’ve attached screenshots of how this is set up in GTM:

Page Author – https://www.dropbox.com/scl/fi/xz1ep9x1p40g49c5t013u/GTM-DLV-Author.png?rlkey=yvwk5dfo5uxlt1enxirrl685g&dl=0
Page Category – https://www.dropbox.com/scl/fi/f6ze7hum6qvjvvhh8v4fm/GTM-DLV-Category.png?rlkey=dnbo3b6swpptriengukfg09uy&dl=0
GTM GA4 Configuration – https://www.dropbox.com/scl/fi/7oz6r9vb415glhk34df89/GTM-GA4-Config.png?rlkey=u9bg4u7z79gs0zq0l1wobks4c&dl=0

And this is what we have set up in GA4 for reporting:

Page Author (you can see this is working properly) – https://www.dropbox.com/scl/fi/ktwel0grhnc7ba3ur8iwa/GA4-Author.png?rlkey=u2d7kq89yic008s4gntxrkpg4&dl=0
Page Category – https://www.dropbox.com/scl/fi/ktwel0grhnc7ba3ur8iwa/GA4-Author.png?rlkey=u2d7kq89yic008s4gntxrkpg4&dl=0

The page I need help with: [log in to see the link]