There is a report from Japanese user that Share button is not activated when he submits photos from Lightroom CC (not Classic).
And I encountered the same problem when I tested.
Before submitting, "Link to Facebook account" dialog appears.
And then, clicking "Move to Facebook" does not work.
I suppose that this button should lead users to Facebook 3rd party apps access setting in the web browser.
But actually, access setting is skipped and in the result, "Share" button is not activated in the "Publish to Facebook" dialog.
How do I activate "Share" button when submit photos from LRCC to Facebook?