"[object Object]" displayed for items array within Analytics 4 debug

I'm migrating a website that currently uses UA analytics configured via GTM to use Analytics 4.

Currently, the Website has the following purchase push event:

({'event':'purchase','ecommerce':{
    'purchase'{
        'currency':'GBP',
        'value':'24.99',
        'tax':'6.3300',
        'shipping':'6.6600',
        'coupon':'',
        'transaction_id':'450048423',
        'total_qty':'1',
        'items':[{
             'name':'Lasher Tools Deluxe Lopping Bypass Shears',
             'id':'119836',
             'price':'24.99',
             'quantity':'1.0000'
        }]
     }
   }
);

I've created a new tag for the Analytics 4 conversion which uses variables populated from the dataLayer of this push. This works fine for everything aside from the items array which returns as [object Object] when debugging via Google Analytics:

Image for Analytics debug

Here's how the items array looks when I view via the Tag Manager debug:

Tag Manager Debug

I can see the 'purchase' event within Analytics, however if I view the 'ecommerce' tabs then the revenue shows as £0.00 and the items columns are all empty which I can only assume is because of the items array issue?