My problems are not over.
When I use the same link (https://www.evernote.com/client/web#?anb=true&) for two different accounts, Account Summary for each indicate that I am using the beta version, but only the Plus account renders Notebooks correctly, i.e., correctly, with Notebooks nested in stacks. However, this Basic account does not render any stacks, instead listing all notebooks in order (e.g., A-Z); and furthermore, lists one notebook (Chromecast) twice, with one indicating correctly (8) notes, the other indicating (0) notes.
I noted in my earlier post that clearing all FIrefox caches resolved rendering the problem. However, this time I am using the Chrome browser, have signed out/signed in, and cleared all browser settings/cache, to no avail.