Not All Fidelity Accounts Will Migrate

I have multiple Fidelity accounts, as do my adult children (Brokerage, IRA's, Roth's, rollovers, them and their spouses) but not all accounts successfully migrate. We do the migration, all seems to go well, and then later one of the accounts will be "unable to update" with the option to "Fix it". I have gone through this "fix it" step many times, seemingly successful, but with no lasting success. The account with "connectivity problems" is a Roth account, one of our 5 brokerage accounts. It last had activity in October. I have been granted access to my kids accounts, for a total of about 18 accounts, which I have to sort through to set up connectivity. I also have seen this problem with one of my grandson's 529 accounts which has had no activity for 5 years (state income tax deductible, we don't live in that state any more, I am the trustee, and I now contribute to his Texas 529). These connectivity problems have been occurring ever since the Great Fidelity Migration. Is this ever going to be resolved?