Desidime app is not visible in multi-tasking app list

Desidime app just disappears once a link from desidime app is opened. For instance, if I open an Amazon link, the Amazon app opens, and when I try to go back to desidime app by tapping on the the multi-tasking button, desidime app is not shown in the list. so I have go back to my home screen and open desidime app again.