Please folllow the steps below to have a try.
1) Update your XMind APP to the latest version;
2) Open your mind map on XMind for Android > make some changes in the mind map;
4) Go back to save the mind map;
5) Transfer your mind map to your desktop and then open it with XMind (2021).
If it doesn't work, please send us a feedback with the file on XMind for Android(Help > Bug Report).