Version: Oxygen Release (4.7.0)
Build id: 20170620-1800
Windows 10 64

Same problem here. Eclipse PDT Outline is empty when opening files using Remote Systems.

One more strange thing is that the tab icons have changed! For example, I see the usual icon for php files with a "P" inside a document at the Remote Systems Explorer, but at the tab of an opened php file I see the system icon, which in my case is from Notepad++!



I will stick back to Neon 3 until this gets fixed.

UPDATE

After some investigation, I realize that PDT has to have a PHP Project to show the outline contents. Well, I'm using Eclipse for many years, and I can't remember that would have to create Project/Remote Project in order for outline to be filled. It's working directly without o project when opening files from RSE to Neon 3 and older versions.