TLDR: There is no fix for this. I had to contact Technical Support and ask for an internal ticket to be opened and was given a ticket number starting with ZX.
Every time I try to watch an on-demand show on the Fios TV Mobile app using my sub-account I am getting an error message. "Activate sub-account" The primary account holder must first activate this sub-account online via Account > TV > TV Management > TV Parental Controls. Once this sub-account is activated, please login again to proceed. Error code: 33-PLYB_UI-180
For context, I am using a sub-account of my Verizon Fios account. The sub-account is active and has activated the email address associated with it. The sub-account can login to the main verizon home website and view all data just fine.
Try to use the iOS app ( Fios TV Mobile) and it just simply gives you the false error message with directions to a page that does not exist. There is no where to activate any sub-accounts on the parental control settings page.
On the website, https://tv.verizon.com/watch/home/, You will receive an error message, "Device registration limit has reached for the Quarter!" while using the sub-account to watch any on-demand TV show, on both the main account and the sub-account.





Good luck to all! Please save yourself the headache and just immediately contact technical support and ask for an internal ticket as this is clearly a bug.
Sincerely, Seaniemac