FileMaker Pro 16
Mac OSX High Sierra
I discovered this when a user reported getting a solid black box when trying to view a SuperContainer link to a pdf. To test and see if the problem was with SuperContainer, I created a completely new file and placed a web viewer on the layout. I pointed the web viewer to http://google.com and went back into browse mode. I then dragged and dropped a PDF onto the web viewer expecting it to render the PDF but instead saw the black box that my user had reported. I then repeated this same process on another High Sierra machine and got the same results. I then repeated this same process on FileMaker Pro 15 with the same file and the PDF rendered as expected. I also tested in FileMaker Pro 16 on a Windows machine and the PDF rendered there as well. I did not test on any other Mac operating systems. It seems this issue is only present in FMP 16 and High Sierra. I tested with both a hosted and local file and saw the black box in both cases.