I resolved the problem. I added the offending shortcode onto another page. It rendered properly. Although I had done it 20 times, I went back to the offending page and resaved after it had worked on another page and then it rendered. Perhaps that’s a caching issue but I cannot imagine what cache it may have been held in. The logic doesn’t really make sense as I had resaved many time previously. How would the shortcode rendered on another page affect a different page?
Regardless, it’s fixed now and I have another thing to try when something similar happens on different sites.
Please mark this as closed.