While using SmartCite you may come across one of your citations having the following error: METADATA ERROR DETECTED. This can be for a number of reasons but the most common is your citation style requires certain data. Make sure that your references have at minimum a title, at least one author, and some type of date (usually publication date).
If you have all of this data and the citation still doesn't work try a different style. If it works in a new style but not the one you chose your metadata should be updated to make sure you have all the fields required. If you run into more issues or have questions about the styles you are using don't hesitate to reach out to support@papersapp.com.