Repeating tasks don't delete and create duplicate entries

Hi,

I'm trying to delete a repeating task. When i click on edit task and uncheck "Repeat" and close the window, instead of creating a single instance of the task and deleting all instances of the tasks on different days, i get duplicate entries of the task on the same day. For example, when trying to end a repeating task "Introduction to Python on Linux", it just creates multiple instances of the same task on monday.