Thank you for the detailed information and screenshot added, @reolsen.

I appreciate the steps you've performed while trying to fix the issue you're getting when clicking the drop-down arrow beside the Select existing or create new section. Since those steps don't make any difference, we can proceed with repairing your QuickBooks Desktop (QBDT). This helps resolve common errors in QBDT.

Here's how to run the repair tool:

Here's how to run the repair tool:

1. First, create a back up of your company file.
2. Restart your computer to make sure there are no programs that may affect the repair.
3. Open the Windows Start menu, then select Control Panel. If you're using Windows 8 or 8.1, search "Control Panel" in the Windows Start menu.
4. Click Programs and Features then Uninstall a Program. If you don't see Programs and Features, select Programs instead. Then select Program and Features.
5. Choose QuickBooks from the list of Programs, then Uninstall/Change.
6. Tap Continue, or Next.
7. Hit Repair, then Next. The repair should start right away, but it may take a while to finish. You can leave it running, and come back once it's done.
8. Once completed, select Finish. Then You restart your computer to complete the repair.

Once QBDT is open, update it to the latest release or make sure you have the most recent fixes and security updates. For your guide check out the instructions from this link.

Then, try clicking the drop-down options under the QuickBooks Accounts column. If the error continues, I encourage reaching out to our Support Team. This way, a representative can open your account securely and be able to review and investigate the root cause of the error. To contact support, follow the steps provided by JasroV above or follow the steps provided from here: Contact the QuickBooks Desktop Customer Support Team.

In case you need related topics about banking in the future, feel free to open the articles from this link.

Get back to me if there's anything you need assistance with. I'm always here to help you out. Keep safe, @reolsen!