It's not a problem in itself, but a sign of the destress the company is in. Evergrande has huge debts and is struggling to pay suppliers. It has started (or received payments for) hundreds of thousands of units that could be abandoned if the company goes bust (many already are), leaving many people with nothing but mortgages for property that doesn't exist.

https://www.reuters.com/world/china/unfinished-evergrande-ap...