Hi there! Thanks for the note.
You can see more about how to use Playstation Vue's channel on Roku here: https://support.playstation.com/s/article/PlayStation-Vue-on-the-Roku?language=en_US
If you're still running into the issue on your device, you might also try removing the Playstation Vue channel from the Roku home screen, restart your Roku device, then add the channel (app) back once more and try logging in again.
You may want to contact Playstation support to report the issue you're running into and request additional assistance if that isn't doing the trick. You can get in touch with them here: https://support.playstation.com/s/contact-support?language=en_US
Feel free to keep me posted if you need more help from there or have any other questions!
Roku Community Manager