After enabling the update permissions on move option in Opus we are often getting a prompt for credentials when moving files on a network drive. The user has permissions to write files in the destination for and indeed the file is moved and does inherit the permissions of the destination folder after they cancel the credential prompt. Because of that, this feels like it might be a bug.
It's because the user has permissions to write the file but does not have permissions to modify the file's permissions. (But Opus doesn't know that until it tries with elevation.)
We have something planned which simply avoids UAC prompts entirely when updating permissions (unless UAC was already triggered to write the file itself) but it's tied to some other changes which are still in development / testing.