Figured out a way around it. It does not appear to be problem with the code.
Use the old editor publish function, create a new version and click Update.
If you copy the updated url and paste into browser, the html will be missing as noted in original question.
So do not copy the provided url, instead, click "Test your code". This will open a browser tab and execute your code as a web app, including the html bits; it words as it should.
The url in the new tab created by the "Test your code" ends with "/dev". Just change this to "/exec" and apparently you will then be executing a new production deployment of your app, with all the bits working.
Don't know what happened with the new editor deploy function as described in original question, I still just get spinning circle. But using this method with the old editor got me back to being able to make changes to my code and publish/deploy the new version.
Strange experience - hope this helps somebody else.
On Tuesday, December 28, 2021 at 9:32:31 PM UTC-5 PirateSteve Brown wrote: