Thanks for reaching out. Just to confirm, does it show 'Subscribed' in the channel page on all the devices? Also, have you tried signing out and signing back in to the account to see if it helps? Let us know.
Appreciate 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.