drag n drop issue

Hi - On a Mac laptop pro in the latest version of Mojave I have created a drag n drop exercise and created correct coordinated drop zones and labels for the drop zones. I have specified that each text label will have one drop zone. However, when I play the activity in Moodle, when I answer correctly and place the labels where they belong, the results show of all of my answers are incorrect with red text and a -1x. Is this a bug or have I possibly missed a setting in one of the set up menus?

Thanks -