When I'm saving pipeline job configuration with pipeline script filled or pipeline script from SCM selected and next I'm trying to edit job configuration again it always load with empty pipeline script (as in attachment).

Job's config.xml file has proper data. The job can be run and will successfully perform all the steps.

If I reconfigure and save it with empty pipeline script, the script will be lost.

After uninstallation of mixing-security-realm-plugin everything back to normal.