I had some issues with this as well, my issues came down to one gotcha and one less obvious thing
the gotcha was the eclipse browser setting was set to use internal browse, 'default system browser' which happened to be chrome. This meant that it would launch chrome but connect to the internal browser. that started working when configered for external browser and explicitly chrome rather than default system browser. Window | Preferences | General for web browser settings
The second issue was around symbolic links. I used symbolic links to link source from a repo into the framework hierarchy. This meant the eclipse project explorer saw one file (the symbolic path) and the debugger saw another (the 'rela' path inside the repo). So breakpoints set in the php explorer version of the file were not seen by the debugger. I solved this by checking out the repo beside the framework directory, symlinking my repo folders into the framework as before but using eclipse 'exclude from build path' on the symlinks so that both php explorer and debugger saw the real path to the file