How to attach files using Form on iPhone

Is there some trick to attaching files using the web Form on iPhone? I seem to be able to select them from my phone, but then there doesn’t seem to be a way to close the selection window without removing the file itself from the form submission?

Thanks.

Ok, so the issue turned out to be that the “Upload” button does not show on my phone when my Form is embedded. I’m using the autosize height embed, not sure that makes a difference.