Xcode Memory Graph Debugging Icon not showing

Question

I've recently started working on an existing objc project and wanted to check the memory graph debugging tool. As I started a debugger with the app I realised it doesn't show in the debugging tools.

I tried it with another project (created a new swift project) and the icon suddenly did show again. But only for this project.

So my question now is if there're any settings in a particular project that can prevent the memory graph debugging tool from showing?

Any hints are appreciated. I tried a lot of different simulators (iOS 9/10/11). I event tried rebooting my macbook because I read somewhere this could help ;-)

I'm using an objc only project with Xcode 9.1 or Xcode 9.2 beta 2.

This is my diagnostics selection in the scheme if that's related:

Answer 1

Step 1: shut down and restart your iPhone. Step 2: quit and reopen Xcode.

This should make the button reappear.