The Backup endpoints may not export the complete issue history

The "backup" endpoints may not export the complete issue history

/api/v1/backup
/api/v2/backup

When adding/removing a Test Set issue in a Test issue both issues will have a new entry in the "Xray Issue History" section (this is correct), however, when exporting this information in the mentioned endpoints only the Test Set history is exported when using the incremental backup.

Steps to recreate:

• Create a Test issue and a Test Set issue in a brand new Xray project. Take note of the created issue time.
• Wait 10-15 minutes
• Go to the Test issue and add the Test Set
• Make a backup export via REST API from this new project and with a modifiedSince property AFTER the issue creation but BEFORE the added links (i.e. 5 minutes after the issue creation time)
• Get the exported zip file and go to the issue history JSON file: only the Test Set issue history is exported. The Test issue history is missing from the file.
• Wait 10-15 minutes
• Remove the Test Set from the Test issue
• Make another backup endpoint call with the same modifiedSince and projects as used before.
• Get the exported zip file and go to the issue history JSON file: only the Test Set issue history is exported. The Test issue history is missing from the file.