Thank you, Yutaka. That fixes it. I even confirmed that turning Quick Start back on will cause it to exhibit the same behavior.
I knew there was a ‘startup’ setting someplace, but I was looking under the ‘Windows’ page of the Customize box.

For the record, I have owned EmEditor for 11 years if not longer, and this is only the second bug I have ever had to report!
Thank you as always for one of the best software products on the planet.