Your comments

Now I see. I was assuming that I should be trying to open by clicking “iCloud“ - which opens only the Textastic folder. “Open...” then “Browse” is the high road, for sure. 

Thanks again!

It’s a pleasure to use an app that works exactly the way I expect, even if it took me a while to see it. 

aha! Thanks!

It took me a moment to understand your response - until I realized that I was supposed to open the document from the Files.app rather than from Textastic - where I had been looking for it. Works like a charm. 

Thanks again.