I have the same issue with the CNN app and commercial breaks, although for me, the screen usually goes blank AFTER the commercial break when the show starts again. Typically, the the commercials show. If I leave it alone, it often revert after the next commercial break, when the show starts again, but will go blank again after the following commercial set. The only way I have been able to force it to display is to exit the show, or the entire app, and then restart the show.
I, too, tried the recommended REMOVE APP, RESTART ROKU (using the Roku System menu), and REINSTALL APP, without any change.
Note that this ONLY happens on my TCL Roku based TV, model 32S327. I have never seen it happen with my external Roku devices attached to other TVs. I use this TV for very few apps, but most of the ones I do use have varied issues that they do not have on the other Roku devices and TVs. Thus, I can't fully blame this on the **bleep** CNN app or on Roku.