Thanks for the inquiry.
When removing the channel, make sure that you restarting the device before adding it back again.
If the issue remains unresolved, I'd recommend reaching out to Netflix directly to report the issue and request additional support. Many channels on the Roku platform are developed and maintained by the channel provider directly, and they'll be able to best assist. If other channels are working correctly, and you only experience this issue on the Netflix channel (app), that is likely an indication that the issue lies within that particular channel. In these cases, the channel provider will need to investigate the issue in order to help resolve it.
You can reach them here: https://help.netflix.com/en/
Thanks,
Danny