It appears Scopus recently changed its export format. Cited references no longer contain the year of publication. This omission causes problems when converting from Scopus for CiteSpace. As a result, you will see a drop in the accuracy of conversion. It is not clear whether the omission is intentional or not.
Before the format change:
Chen, C., Citespace II: Detecting and visualizing emerging trends and transient patterns in scientific literature (2006) Journal of the American Society for Information Science and Technology, 57 (3), pp. 359-377;
After the format change:
Chen, C., CiteSpace II: detecting and visualizing emerging trends and transient patterns in scientific literature J. Am. Soc. Inf. Sci. Technol., 57 (3), pp. 359-377;