i have the same problem,
i'm old user of blockchain, sometimes before it was not loading balance for two reasons :
- one of your wallets has negative balance because of double spend, usually happens when there is unconfirmed payments, it returns and send again to other wallet, then it try later to send previous transactions, this makes your wallet send payment more than once to diff wallets.. this usually get solved within few days when node reject one of two transactions and confirm the other.
- the other reason, which i'm not sure if it happens because of it, your wallet has many imported wallets, i'm not sure about this, but this happen to me last week, i checked all wallets and all has +0 balance. that's why i guess reason is having many wallets. but maybe i'm wrong about this reason.
What i'm facing today, is i can't even login into my two accounts on blockchain, i contacted blockchain support and waiting for reply.
Yes, both of my wallets were also created years ago so they both have imported addresses. On the one that I use the most I cannot login and on the other one I can login but some things don't load correctly. I made transactions before this with the imported addresses but they all are confirmed many times so it cannot be this.
as i'm writing this i noticed that it worked succesfully, i kept it on loading for like a hour and it logged me out and i just pressed login again and it logged me instantly in.