Please use code tags in your posts.
If you’re going to implement IDragHandler, you should always also implement IBeginDragHandler and IEndDragHandler. Unity seems to assume that these interfaces go together, and if you don’t implement all 3 of them then it doesn’t seem to use them correctly.
In those interfaces, the function for the end of a drag is called OnEndDrag.
I’ve never heard of OnDragRelease and don’t see it in the docs, so I’m thinking you’ve probably just got the name wrong.