China particularly worried about enforcement
Chinese officials aren't as optimistic as Trump about a trade deal because of Trump's habit of making last-minute changes.
The trade deal looks like a good one for Beijing, since it largely spares the government from making substantive changes to its economy. But some of the biggest details - like the enforcement mechanism to ensure China complies and the timing for the removal of tariffs - still haven't been hammered out. Beijing officials are wary that the final terms may be less favorable, especially given Mr. Trump's propensity for last-minute changes, according to two people familiar with China's position.
The report says China is wary of planning a trip to Mar-a-Lago without a clear understanding of the final details. Xi doesn't want to risk going there and leaving empty handed as it could leave him looking weak in the eyes of his domestic audience.
They also note that China has repeatedly thought they had a deal with the US at various times in the past two years only to walk away empty handed.
Here's the NYT story.