I opened Edge Dev this morning to find it had updated "This is Microsoft Edge Dev Build 18.104.22.168"
When I followed the page's suggestion to test out the PDF reader using a local pdf, instead of opening the .pdf file, I got the "Save as" dialog box.
I've tried opening it from the Explorer window using the "right-click" menu to "Open With" and I've attempted opening the file directly in the browser. In both attempts, I continue to get the "Save as" dialog.
If I navigate to a .pdf file on the web and attempt to open it, I still get the "Save as" dialog. When I complete the save, the file has been downloaded to my Downloads folder.
But if I attempt to "Open file" from the button at the bottom of the page, I get another "Save as" dialog with the new filename suffixed with the "(1)" for a second copy of the same file.