This may be related to the YouTube Gaming subscription update, the full announcement is here: https://goo.gl/zfgfC4 . Let us know if this doesn't seem like your issue or if you're unfamiliar with YouTube Gaming.
Thanks for the info. Could you file a feedback report with these steps: https://goo.gl/1ckkO5 ? While every individual report may not get a direct response, we do review everything and use the details to investigate and fix issues.