This is because it is difficult to create a comprehensive list of operations in the cuDF and Pandas libraries. The API is large enough to be difficult to track effectively. For any operation that operates row-wise like fillna or query things will likely, but not certainly work. If operations don’t work it is often due to a slight inconsistency between Pandas and cuDF that is generally easy to fix. We encourage users to look at the cuDF issue tracker to see if their issue has already been reported and, if not, raise a new issue.