Per the documentation:
^SomeRem: Matches Rem that you can see if you open the document SomeRem. This includes Rem in fixed portals, but not search portals, and does not include Rem that are children of collapsed Rem.^^SomeRem: Matches Rem that are direct descendants of SomeRem. This does not include Rem in portals, but does include Rem that are children of collapsed Rem.
It’s annoying enough to have to use (^~ or ^^~) to catch both portals and contents of collapsed rem, but that also seems to imply that there is no way at all to search for Portals that are inside collapsed Rem. Does anyone have a workaround?