I have no issues with Windows 10.
Do you mean that you're able to cast from Windows 10 to your Roku, using either the right-click context menu or the "cast to device" option in the Edge broswer? Doesn't work for me and I haven't even been sure if it's supposed to work with Roku!
I just go to the Action Center, click "Connect", I see my Rokus (I have three that will work), pick the one I want to cast to, PC sees Roku as a second monitor. I've been Successful with two devices so far. Alienware laptop and an Asus tablet. Just connected it as I was typing this. I have the 1607 update for Win10 as well.
BTW, don't try using PS4 remote play, lol. It works, but the delay... But in a way, I can use Win10 PS4 Remote Play to cast to Roku.