Missing add browser button

Apparently, to add an unsupported browser, I can click "Add Browser".

But there is no "Add Browser" button:

The log file goes on an on about "Verifying browser", followed by, "Additional error context: Process is not cmd.exe"

It does note that the browser is signed by OSSign, which is correct for Librewolf, and it is looking at the correct copy of librewolf.exe. The parent process of that being cmd.exe is up to Microsoft. I would think that since I've clicked on it, the parent process would be explorer.exe in the normal case. I did try launching a cmd.exe terminal window and running librewolf from there, but that did not help.