If it only happens on that one channel, then the channel is the cause. Note that the Roku 3 (4200) was released in Mar 2013, while the 4230 Apr 2015. In both cases that's an old player, and it might simply be unable to handle the latest versions of the channel well. The channel developers often claim their channel works on all Roku players, but that simply isn't the case with many of them. I searched NBC's web site for any list of supported players, but could not find any. They simply say they support Roku devices.
You might try contacting NBC and complain, but I doubt anything would change. My guess is they would tell you to buy a new player.
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