2 things here.
Is it possible a user saves/bookmarks/sits on the page(midway in funnel) then returns or continues after 30 mins ?
If your SPA doesnt kick them out then maybe you are seeing session limitation here.
Also does you SPA app kill the referrer if a page is manually refreshed or a user click back and forth in browser?
How are you getting Pagename in SPA? routing rule or?