Mine seemed to be loading okay - sometimes the website has gone blank for me when my session has timed out, and I need to log in again - so might be worth trying logging out and back in if you haven’t already.
I actually quite enjoy Cater Allen - whenever I need to contact them, they’re helpful and quick. And I really like that the online banking is plain and not trying to sell me new products like some other banks.
Cater Allen Limited itself is a separate company to Santander UK plc and has a different banking license. That said, it has no employees as everyone is employed by Santander UK plc.
I use open banking in Lloyds to view my Cater Allen GBP / Euro balances as some providers (inc Santander) have a limited choice. Be aware you won’t see any live changes as they take a day or two at least to update transactions.