I'm having the same issue here. After going through the authentication process in the window that pops up, the page loads blank. Inspecting the page source, it is a QBO page that is failing, not a Shopify page. In your reply here, you mentioned contacting the Shopify Balance team to make sure they allow QBO connections. Why would it even show up in your list if it wasn't allowed?

Anyway, this needs to be escalated to your engineering team to figure out why the QBO OAuth process is failing after authenticating with Shopify. There are a lot of us who use the Shopify Balance account as our primary bank account as it is easy, integrated with our Shopify stores and doesn't require the ridiculous steps that classical business checking accounts still require in 2024.