Saved filter results discrepancy between JIRA search results and Xray Reports

An easy scenario to replicate this problem is:

• create a JIRA filter targetting the requirement issues from a specified sprint;

  project = <YOUR_PROJECT> AND sprint = 67 AND issuetype = <ALL_REQUIREMENT_ISSUETYPES>

• navigate to the Xray Reports -> Overall Requirement Coverage Report and on Filter -> Saved Filter and input the previously created JIRA filter;
• Compare the filter results between the JIRA issue search and the Xray Report, and the Xray Report will display less entries