The error that is occurring in Merchant Service Deposits (stuck on “Please wait… We’re matching your deposits to QuickBooks Desktop records”) showed up with the last update (QuickBooks Desktop 2020 R14).  I have reinstalled the QuickBooks software and by reinstalling the update components individually have isolated the error to the “maintenance” component of R14.  I have also run the various utilities from the QuickBooks Tool Hub, with a full reboot between each run, and that did not fix the problem.