Thanks for reaching out here in the Community!
Does the issue only occur only in the Fox channel or across other channels installed on your Roku device?
If you haven't tried it yet, you can remove the affected channel and then re-install it. To ensure the process is successful, restart your device before adding the channel back in. We would recommend doing this from the Settings menu by navigating to Settings > System > Power (If you do not see a Power submenu, skip to the next step.) > System restart.
We recommend starting here to troubleshoot any channel playback issues: How to resolve a channel playback issue | Official Roku Support
Please keep us posted and we'll continue assisting you from there.