Only first genre is imported when matching or metadata requested from a Custom Metadata Providers

I have a matching and metadata requests working but when passing in the genres only the first is being populated. I have tested this by rearranging the array and it always picks the first one (and removing any existing). I’ve used the list from the example in the api document:

[
{
“tag”: “Adventure”,
},
{
“tag”: “Comedy”,
},
{
“tag”: “Science Fiction”,
}
]

Any ideas?