iBooks not synching PDF files across Mac and iPhone
I just added two PDF files to iBooks on my Macintosh. I want to be able to read these PDFs in iBooks on my iPhone. However, they don't appear on my iPhone.
Initially I looked in the PDF category in iBooks on my iPhone. They weren't there.
Since that didn't work, I created a new Collection in iBooks on my Mac and added the PDFs to that Collection. Let's say I called the Collection "Companion Documents". On my Mac it has two PDF files in it.
When I look at iBooks on my iPhone, the "Companion Documents" Collection is visible, but it is empty. It doesn't contain any PDFs.
These are not large files. One is 371 KB, the other is 2 MB.
How can I get these files to appear in iBooks on all my devices?
I'm running the latest version of High Sierra on my Mac (10.13.2) and the latest version of iOS on my iPhone 6 (11.2).
Thanks in advance.
iPhone 6, iOS 11.2