Thanks for trying those steps. Can you tell me a bit more information please? When you described the Bank account dropdown as frozen, were you referring to the dropdown used when switching between bank feeds or something else? If that's the case, you can still change between the feeds by clicking on the small arrow beneath the 'Add Account' button - this will expand your view and enable you to select different accounts.
Alternatively, I would also suggest reaching out to our Support Team so they can record this and effectively troubleshoot this issue. You can contact them on 1800 046 038, or by:
In your QuickBooks Online, click the Help menu in the upper-right corner.
On the Search tab, click an article and select Contact us at the bottom. Then, enter the details of your concern.
Choose how you would like to connect with them: either via Callback or Chat.