I am not able to delete single text messages in a conversation since updating to iOS 8 Before iOS 8 I could click on a text, get the More option and see a trash can on the bottom of the screen. This would allow me to delete a single text from a conversation. 

Now there is only a camera in the place the trash can used to be. I have reset my phone and the trash can comes back, but only briefly. Today I totally erased my phone and the ability to delete single text messages from a conversation still does not last more than a few texts.

Is there a way to make this feature persist?
If you double-tap on a message rather than single-tap, up pops a "Copy/More..." selector, and hitting "More..." gives you the trash and forwarding arrow icons (along with the ability to select other messages to delete at the same time.)

If the icons do not apear, or if they stop apearing, there is something not working the way it does for me. Some people find that the icons re-appear after a restart (if only for a short time). Perhaps completely "quitting" the application would help? If you double-click on the home button, and then "upswipe" the Messages window does that have any effect when Messages is re-started?