Check the firmware version on your Rokus. If you have version 7.7 then that is probably the problem. Read some of the other threads and see if you can get the downgrade to 7.6.
I haven't had any issues with Netflix on my Stick or 4 or Roku TV, but I decided to test my old 2 XS last night. It does have 7.7 on it, and it too played Netflix without issue.