Does the issue only occur on All 4 channel or across other channels installed on your Roku device?
Did you restart your Roku device before re-installing the channel? This is to ensure you have a clean channel install when adding the channel back. Restart it from the Settings menu, Settings > System > System restart.
If you are still unable to play videos from one channel after attempting the suggestions above, videos from other channels play fine, contact the channel provider's customer support team to report the issue and get help. Channels on Roku are maintained by the channel developer themselves. In this case, there's likely an issue within that specific channel that needs to be addressed with an update from the channel developer.