Thanks for the post.
Does the issue only occur on AMC+ or across other channels installed on your Roku device?
If you haven't tried yet, try removing the affected channel then re-install it. To ensure the process is successful, make sure to restart your device before adding the channel back in. We would recommend doing this from the Settings menu by navigating to Settings > System > System restart > Restart.
For detailed instructions, refer to this Support link: How do I resolve channel playback issues?
Please keep us posted!
All the best,
Roku Forum Moderator