Thank you for your assistance, but I'm still having issues.

I am a long-time Pro Advisor using QB Accountant Desktop 2020. This same error happens in v. 2019 and with multiple client files. I had another staff member attempt to recreate the error on their workstation and they did not have issues.

I attempted to repair the installation of v.2020 which failed, so I completely uninstalled and reinstalled 2020. It appears to be up to date (R10_45). I did note that the other staff member seems to have a different version on the "Update QuickBooks Desktop" window. My version is v.31.0.4001.0 while she has v.30.0.4010.0. So, it would seem my version is more current.

This began to happen when I had to log in online when a client sent me a QBX file.

This is obviously crucial to my practice as we enter our busy season.