Sure, we'd like to help. Did any of the channels contacted you saying they were blocked? Also, if your channel has blocked any contact it should be in the blocked contacts list here: https://goo.gl/ideyPg . Keep us posted to help you further.
Thanks for the info. Please send a feedback report directly from YouTube: https://goo.gl/WdI0BK . While every individual report may not get a direct response, we do review everything and use the details to investigate and fix issues.