I was unable to recreate the issue. Perhaps it occurred after my computer running for 2 weeks of heavy use without reboot. I will attempt again next week and report back. But it appears this may be a fluke.

-- Thank you.

Thanks for your report.
I have sent you an email with a debug version of WinSCP to address you have used to register on this forum.

<Try to describe precise steps that lead to the problem (where do you click, what keys do you press, what do you see, etc.)>
<If relevant, consider attaching a session log file or a screenshot)>

WinSCP 5.5.1

Error message:
Invalid access to memory.

Cloned a saved SCP site, saved under a new name. Attempted to connect but the site was not in my hosts table (no DNS entry for it) and failed. Added site to hosts then attempted to connect and received this error.