Photos not syncing from new MacBook Pro to iPhone
I am using all up-to-date software (iPhone 11.2.6; MacBook Pro 10.13.3 High Sierra) but photos are no longer syncing from my MacBook to my iPhone via iTunes. I am repeating a sequence that's worked in the past and is exactly as described in Apple Support -- connect phone, click on phone icon on laptop's iTunes, see the folder I want and select it, click Sync, but the photos do no longer come across to Photos on the phone. I like to keep a selected set of photos on my phone. What do I need to do to get them there? Is this a result of upgrading my iPhone recently??? Any ideas what's going on and how to fix or get around it?
(Note: I am not trying to do any of this via iCloud nor do I wish to.)
Thanks for any help anyone can provide.
MacBook Pro with Retina display, macOS High Sierra (10.13.3)