Seems to be working now. Thanks!

You are mistaking file panels:
https://winscp.net/eng/docs/ui_file_panel
with tabs:
https://winscp.net/eng/docs/ui_tabs
You want one (remote) tab with two (local and remote) panels.

You now have two tabs, the first (and the default upon start) is a local tab (two local panels) and the second is remote tab (local and remote panels). You want to close the first one and keep only the second.

I guess I’m not stating this clearly. I want BOTH tabs (local on left and remote on right) to appear when I launch WinSCP.

I don’t understand the distinction between an application shortcut & workplace shortcut. But my guess is that I want a “workspace” shortcut. As I said, I’ve only done this once, years ago.

Just now I created another workspace shortcut, using the instructions at https://winscp.net/eng/docs/workspace#save. Both the local and remote panels were showing properly when I saved it. But when I clicked the workspace icon on the desktop, WinSCP showed two copies of local server. This is the same result was getting before. What am I doing wrong?

Depends, what kind of shortcut it is. If application shortcut or workspace shortcut.

Anyway, as I wrote before: you have two tabs, the local tab that you do not want and the remote tab that you want. Just close the local tab (using the small "X" button on the tab).
See https://winscp.net/eng/docs/ui_tabs#working

Yes, I am using a “shortcut,” if that’s the right term. In fact, the shortcut has been on my task bar so long I forget how I created it. What it used to do is open the Cyber Hymnal site on the right panel & the local machine on the left.

Should I delete the shortcut & recreate it? If so, can you refresh my memory on how to create a shortcut that opens a specific site? I’m not sure where to look in the documentation for that procedure.

No matter what, if you do not want the local tab, just close it!

So WinSCP is opening a workspace with two tabs (local tab and “Cyber Hymnal” remote tab).
WinSCP should not automatically open workspace, when started normally.
So I wonder, how do you start WinSCP? Haven't you (maybe by mistake) created a desktop shortcut to open a workspace in WinSCP? And you are starting WinSCP using that shortcut, instead of the regular WinSCP application shortcut?
Also, your post implies, that sometimes "app is working correctly". When is it working correctly?

Screencast is screen recording. See https://winscp.net/eng/docs/reporting#recording

No, the login dialog does not appear. WinSCP just seems to launch normally, and I can’t tell anything’s wrong until I see that both left and right panels show the same folder on the local computer.

The only dialog that opens is the one asking for the master password (same dialog I get even when app is working correctly). No error message ever appears.

Don’t know what a “screencast” is, so I’ll post screen shots (forum software shows them in reverse order). Notice that initially, that both left and panels show the same files on the local machine. When I click the button that says “Cyber Hymnal” (above the left panel), WinSCP then displays the remote server files in the right side panel.

I’ve also included the dialog showing the program version number.

Let me know if there’s anything else I can provide.

So does the Login dialog pop up on start or not? Can you post some screenshots (or even a screencast) showing what exactly is happening when you start WinSCP?

No, my Preferences/Window dialog is identical to the example, with one difference: The last option (“Display tips on startup”) is disabled (but checked).

The “Show Login dialog on startup” box is checked..

Haven't you by mistake disabled automatic Login dialog popup?
To re-enable it, check Show Login dialog on startup and when the last session is closed:
https://winscp.net/eng/docs/ui_pref_window

How can I make the remote site appear in the right-side panel of the Commander interface?

WinSCP used to show the local computer on the left and the remote computer on the right side when I launched WinSCP. I don't know what changed, but now both left and right panels show the local computer when I launch WinSCP. There’s a tool bar button (next to the “New Tab” button) with the remote site name, and the remote site appears when I click the button. But sometimes I forget to click the button and think the right panel already shows the remote site, which gets extremely confusing.

How can I make the remote site display automatically in the Commander interface right-side panel when I launch WinSCP?