Why can't my phone delete conversations?

Been experiencing this issue since iOS 8.2 wherein I am unable to delete conversations in the Messages app. After attempting to delete specific messages, the app bugs and deletes all messages in the app and then I am unable to send and receive any messages. Restarting my phone lets me send and receive messages again but the phone restores all the messages I attempted to delete. Tried resetting my network settings but the issue persists. Please advise and thank you very much!