I'm here to help check why you cannot access your customers accounts.
If you're an accountant and can't access your customers/clients accounts, please ensure that you're still connected and not removed from your customers' account. If verified that you're still connected and the problem continues, we can perform some basic troubleshooting steps.
First, you can access/login your account using a private browser and try accessing it from there. This helps verify if the issue is within the browser you're using. To access your account using a private browser:
Google Chrome, press CTRL+ Shift + N
Mozilla Firefox: press CTRL+ Shift + P
Internet Explorer: press CTRL+ Shift + P
Safari: press Command + Shift + N
If it works fine, you need to clear the cache of the regular browser you're using.