I am still confused: Two points.
1. There is a kodi video test addon that tests widevine, it runs perfectly happy at 1080p.
2. In our country (NZ) we have TVNZOndemand plugin that uses widevine (won't run without) and it plays 1080p content also.
Note: I have installed Netfix & it's version of widevine, before using it on tvnz-ondemand ..
So why is the issue just Netflix.