I have setup a test database to work with the data api. I have given it the right permissions etc and can GET (read) and POST (add new) items with Postman but when I PATCH (modify) I am unable to change anything and get 404 response.
If your results are from Postman, then potentially the issue is that there is nothing set in the When field (highlighted in red). If you want it to be everyone, use current date/time is current date/time, which will always be true.
The PATCH URL appears to be invalid. Don’t know if it’s just a forum typo or what, but that would certainly give a 404 (resource not found) if used as it appears in your post.