Continuing with the update connectivity issues, I took one computer that was connecting happily to my Kobo ereader and iPhone 5S. I forced it to update using the
Windows 10 Anniversary Update Assistant and reconnected the Kobo and the iPhone 5S.
Much as I expected, I get an empty drive for the Kobo's internal storage and the iPhone shows no files/directories.
So my recommendation not to update is still in effect.