However the other address has way more BTC connected to it.
Presumably, that's their hot wallet.
I'd used this wallet maybe 2 years ago and I have never been encounter such a problem until I switched to a non-custodial wallet instead of a web wallet because I feel unsafe using a web wallet. It might once you have a problem is not just easy to fix for them, in short, they had poor customer support and you're very lucky once you get answered from them.
I suggest you guys stop using a very buggy web wallet, there are too many open-source wallets out there to use, it's safe and you have full control over your private key.
Additionally, be aware of the web portal blockchaintradingfx.com. These guys are SCAM. Get away of them.
This isn't the official web portal of the blockchain wallet, it's obviously a scam site if you will use them.