I've used Classic Edge as my PDF viewer for a while and why it doesn't do the best with editable PDFs it was functional. I found out today that while Edge Dev renders editable PDFs great when you try to save them after makeing edits it downloads the file instead of saving the edits back to source file. Took me a while to figure this out. I kept editing a form, saving it, then reopening it to find none of my edits in it.
This is different from the Classic Edge feature that allowed you to write on a read-only PDF which I know is the topic of another thread. This is for PDF forms that are published with editable sections embedded into them.
@BruceLH thanks for providing this feedback. Currently the save button just downloads the original copy of the file from the web. Edits on PDF forms are not saved. We are working on getting this functionality up and running and it will be available in coming months. Please stay tuned.