Could you try to substitute the space for a carriage return
PatternCount ( Door Schedule::Adjoining Rooms ; Substitute ( Room Data Sheets::ROOM NO ; " " ; "¶" ) ) > 0
Thanks for the suggestion Phil. Didn't work I'm afraid, when I replaced the filter with your suggestion, the portal still didn't displace results separated by a space or with a space at the beginning/end of a line
I'm curious as to why the requirement that the adjoining rooms be listed in a single field let alone a list separated by spaces. A related table that lists adjoining rooms would make more sense to me here.
While pattern count should work with the sample data shown, I'd be inclined to use:
Not Isempty ( FilterValues ( Substitute ( Room Data Sheets::adjoining Rooms ; " " ; ¶ ) ; Room Data Sheets::ROOM NO ) )