Yes, I can see the images that I am referring to in the link you provided. The most recent upload that I cannot access in Spark is the collection 'creamy kale gnocchi'.
I am working with lightroom classic 9.2 on MacOS Catalina 10.15.2.
The images are set to sync with lightroom mobile, but I don't use the mobile apps - only desktop.
I took a look at the troubleshooting doc you provided and the first instance appears to be for older versions or lightroom, and for the second, I have tried signing out and signing back in and I do keep my apps up to date, run on the same network, and I do not leet me computer sleep while syncing.
Quote "The images are set to sync with lightroom mobile, but I don't use the mobile apps - only desktop."
Just so you are aware you can only Sync One Lightroom Classic Catalog to the Creative Cloud at any point in time. So you cannot sync from Lightroom Classic application in one computer to Lightroom Classic application on another computer.
One computer can be running Lightroom Classic and the other one Lightroom (the cloud-based photo service}.
Regards, Denis: System iMac mid-2015, 5K 27” monitor, macOS10.15.7: LrC 10, Lr 4, Ps 22.0,; Camera OM-D E-M1.