I don't see a Portfolio card on a company profile
The Portfolio card only appears once at least one other company has mapped this company as its investor. If no portfolio companies point to it yet, the card won't show. Add an investor entry from a portfolio company's profile to create the relationship, see How to Mark a Company as an Investor.
An investor entry is mapped to the wrong company
This is a remapping situation, not a rename. Open the investor entry and point it to the correct company profile. Every rollup tied to that entry, jobs, deals, placements, contacts, and portfolio membership, updates immediately to reflect the new mapping, with nothing left over from the old one.
I don't see the four-option filter dropdown on Contacts, Jobs, Deals, or Placements
This dropdown only appears on company profiles marked as an investor. If the profile you're viewing isn't an investor for any other company, it keeps the standard, unfiltered card behavior instead.
A portfolio company's own portfolio isn't showing up
This is expected. Portfolio depth is capped at one level in this release, so if a portfolio company is itself an investor with its own portfolio, that second layer doesn't roll up into the original investor's card, filters, or Job Company Investor column.
Investor entries aren't being added automatically
Automatic enrichment only runs on the AIRA Plan or with JCA enabled. On other plans, every investor entry needs to be added manually, see Investor & Portfolio Tracking: Plan Differences.