Hereby bumping an existing issue with the Portfolio integration in Lightroom. Although the topic (1) was marked solved by the OP, the issue persists for other users.
It is most annoying because it is preventing me from adopting and further using the Portfolio product. I really hope this will land on the developers backlog and get fixed soon.
Whenever I try to add a LR image to an existing Portfolio project using the "Share to Adobe Portfolio" feature, I get the error message "Photos not synced", "Original photos must be synced to the cloud before publishing". All my photos are synced yet this problem continues (on multiple devices).
I have tried to use this feature on multiple devices with the setup described below.
The issue happens both to photos which have been edited in LR as well as SOOC photos (RAW). Camera used is a Sony Alpha A7RII.