Invalid Password Prompts on two of three accounts associated with Xfinity account (fixed now i think, but confused as to what happned)

I am trying to figure out what happened here and at the moment I think this is fixed but I want to know what may have happened.  I admit I do not have all the info so I am going on what I do know.

Accounts effected - Master and one of the sub accounts

Accounts without issue - ... Mine ... one of the sub accounts (aka non-master)

the issue is on different machines. even after clearing temp files and cookies, i kept getting (family members really but i confirmed it on my own laptop with their accounts) "invalid passwords" on their account ...the overall master acct AND one of the sub accounts.

What i did was login to the Xfinity app with the master account with the SAME (no typos) ... logged in no problem instantly ... .i went back to my own computer that I confirmed the "invalid password" prompt with and i cleared cookies and cache (just in case) and used the same exact email and password ... THIS TIME it worked and logged in ... .I have NOT tried the second "sub account" yet.

I am just confused what happened and why ... my fast idea at the time ... fixed things