fileInput button in Shiny not allowing pop-up in Safari 14.0.1

I just updated to Safari 14.0.1 on a Mac (MacOS Mojave 10.14.6), and my inputFile button no longer seems to elicit the file search pop-up. The app works fine on Chrome. And yes, I've disabled all content and pop-up blockers on Safari for this website.

The app is at:

And all the associated code is at the Github address indicated on the app's landing page.

I'd appreciate any direction here.