Xray Cloud uses entities (Jira issues) that are managed and hosted direclty by Jira Cloud.
It also uses its own database and support infrastructure, which are hosted in properly secured cloud vendors.
This means that Xray Cloud and Jira Cloud need to communicate using secure APIs (e.g., for obtaining issues, to be notified upon changes on some issues).
However, due to connection/networking issues or simply because you have disabled Xray for some time, the Xray Cloud database may be out-of-synch and you may need to enforce a synchronization, which we call "project re-indexing".
When out-of-synch issues are detected when using Xray, a warning message will be display. You as the user can then take action to resolve it. If a full project re-index is required, the warning message will provide a link to the project settings so you can perform the operation.
Please note
The way apps are deployed and run on the Cloud follows a different approach from the Jira Server, due to the way the Jira Cloud architecture was designed by Atlassian.
On the Jira Server, apps such as Xray run directly in the web container of Jira. On the other hand, the Cloud apps must run outside of the Jira Cloud infrastructure and must use secure APIs in order to interact with Jira.
Force a re-index
A re-index can be enforced from Re-Indexing section of the project settings. This operation may take some time, depending on the size of your project.
Cancel an ongoing re-index
An ongoing re-index may be canceled. However, this operation actually interrupts the re-index, which may leave some data partially indexed or completely unindexed at all.
