MS Graph: Cannot update Person or Group Field in Sharepoint list

Question

I am trying to update the contents of a person or group field of a specific item in a Sharepoint list. However searching through the docs I could not find any examples, so I created a flow that does just that to take a look at the code. Pasting the code into MS Graph Explorer returns a 200 but does not change anything. Updating fields like the title, links or whatsoever work. I am using a PATCH request with the url:

https://graph.microsoft.com/v1.0/sites/XXXXXXXXX/lists/MYLIST/items/4

and the following body:
{
"MYPERSONORGROUPFIELD": [
{
"Claims": "someuser@Company portal .com"
}
]
}

Answer 1

Say, you have field "Category" then if it's lookup field is single, then you want to try the below and see if it helps.

Url: https://graph.microsoft.com/v1.0/sites/{site-id}/lists/{list-id}/items/{item-id}/fields
Method: PATCH
Body: {
"CategoryLookupId": "1"
}