Hello,
Thank you for contacting the Community. According to our documentation, LeanIX currently supports XML formatting for diagramming, so this should not present a limitation at this time.
Draw.io is among our supported platforms, and diagrams created there should be compatible with the LeanIX diagramming platform without any loss of data or visual changes.
I'd recommend opening an SAPForMe support ticket at your earliest convenience. Our support team will be able to investigate this issue further, access diagnostic information, and help resolve the discrepancy you're experiencing with the XML format API method.
SAPForMe link: https://me.sap.com/
Thank you, and I hope you have a wonderful rest of your week!
Best regards,
Niral Mehta