@jacobs, I tried removing the Quicken preferences file as you suggested, but that did not affect the behavior of this one account opening to an old transaction. I restored the saved copy of the old preferences file. I did notice that after the last Quicken update a few days ago, the transaction on which the register opens moved “up” by one to the next most recent transaction. I'm not sure if the update caused this. I noticed the change some hours after I updated. I still suspect Quicken on the Web is somehow involved. Perhaps removing this account from syncing with the cloud and restoring may provide more info.
Turning Quicken on the Web off did not affect the behavior of this one credit card account opening to an old transaction and returning to View by Dat. Puzzling.