PhpStorm 2016.3 + Xdebug 2.5忽略了除第一个断点之外的所有断点

After a php update from 5.6 to 7.1 I'm having trouble using Xdebug with PhpStorm.

The problem manifests itself as follows:

I set a breakpoint which successfully stops the execution at that point. I am able to see all the variables etc. Now after hitting this first defined breakpoint it seems like none of my further inputs do matter. I am not able to step through the code nor can I set further breakpoints. The interesting thing about this behaviour is that PhpStorm seems to stop always at the same lines of code (which do not contain any breakpoints) after hitting that first breakpoint.

What I've done so far:

• Checked Xdebug relevant settings using https://www.jetbrains.com/help/phpstorm/2016.3/configuring-xdebug.html
• Ensured that PhpStorm language settings point to php 7.1
• Tried path mappings (which in my case shouldn't be necessary)
• Invalidated PhpStorm cache
• Run the PhpStorm Webserver Debug Validation with success

Edit:

How is it possible that my first breakpoint gets respected and any further actions are ignored? I assume that my configuration is OK as I am able to listen to the debugger.