https://tracker.moodle.org/browse/MDL-71145 seems not fixed perfectly yet. I was able to confirm the issue on Moodle 3.10.7 and Moodle 4.0 (qa.moodledemo.net) with the attached question from MDL-71145. This issue should really be fixed, since this means that correct student answers might accidentally be marked wrong.

Steps to reproduce (steps bold which are different to the MDL-71145 issue):

1. Create a course.
2. Go to the Question bank.
3. Import the attached question XML file *from https://tracker.moodle.org/browse/MDL-71145.*
4. Preview the imported question.
5. Turn on the Responsive mode in the Browser:
   1. Open browser developer tools
   2. FInd the Responsive mode button (Top left next of dev tools looking like an phone + tablet in Chrome)
6. Set the responsive resolution to 1366x768.
7. Place three drag merks by Dragging the marker from the drag home area to the drop area.
   1. Verify that there are 3 markers in the drop area.
8. Navigate to another question in the exam
9. Set the responsive resolution to 360x640 while you are in another question
10. Navigate back to the ddmatch-question you used in step 7.
11. Drag the marker from the drag home area to the drop area.
12. Verify that there are 4 markets in the drop area.
13. Remember or note the position of these 4 markers.
14. Press the Save button.
15. Now the position of the markers has changed/the 4. marker is lost.