Photos not syncing from iPhone to Mac

I have switched off and on iCloud and sync on both Mac and iPhone, restarted both etc. I have tried all tricks and tips but still the newer photos don't show in Photos on the Mac.

Mike, the switching on and off may be the reason, why the updating never finishes.

When you turn iCloud Photos off and then enable it again, iCloud Photos will start a new upload to iCloud and merge the complete library again into the existing library. You will just have to wait longer.

Your new photos will start downloading from iCloud to your Mac, once the new upload has finished.

But Catalina has brought an added complication. There may be photos in your library, that are not compatible any longer with Photos on Catalina. You have to identify any video or image, that is an unsupported format and cannot be processed any longer by Photos. These items need to bereaved from your Photos Library and converted to a compatible format. Look for old videos or PDF files, or audio files.

And check the status of the upload to iCloud. Search for references files or files "unable to upload" with smart albums as described here: About the status bar in Photos for macOS - Apple Support

I made some experiments on my iPhone with iOS 13.3 and my mAc with macOS 10.14.6 Mojave:

• On Mojave I can still import PDFs to Photos 4.0, but I cannot edit them. When I open a newly imported PDF on my Mojave Macs, I get this error message:
• 
• On iOS 13.3: When I try to save a PDF from iCloud Drive to Photos, the PDF cannot be saved to the Photos Library.
• And when I try to edit a PDF on my iPhone I am getting the same error message as in Photos 4.0 on Mojave.
• The Photos.app at www.icloud.com does not allow me at all to upload a PDF to Photos, neither on my Macs with Mojave (in FireFox or Safari), nor on my Catalina Macs.

As you are on Mohave and not Catalina, it should still be syncing, even with PDFs in your library. but the changes in Catalina may have repercussions on older devices. icloud.com should still handle pdfs, because it needs to support older systems, but Photos 5 can no longer handle pdfs. as long as you are having pdfs in your photos library or in icloud photos, they may be causing problems. your iphone with iOS 13 has already the same restrictions as Catalina Macs. My photos library did not sync with iCloud, until I removed the last PDF file and some old quicktime movies from the icloud photos library and the catalina photos library.

How is your Mac connected to the Internet? Are you using WI-Fi or a cellular connection?

Did you enable a firewall or an antivirus filter, that could be intercepting the connection to Apple's cloud servers?