PhaseOne has officially pulled the plug on Media Pro. They encourage users to migrate to Capture One Pro catalogs. There are some caveats.

https://www.phaseone.com/en/Products/Software/Capture-One-Pro/mediapro-discontinue.aspx

There is a bug in importing MP catalogs into C1. Hierarchical keywords in MP are imported as flat keywords in C1. I opened a case with PhaseOne arguing they have a responsibility to fix this since they own both products. C1 catalogs are a forklift of MP cataloging that came from MP after PhaseOne acquired it. Let’s hope PhaseOne fixes the bug. There will be a lot of disappointed C1 users when they find their MP hierarchical keywords got flattened during import into C1.

Also missing during import are People annotations. You will have to filter by each person in your “People” collection, and make sure their is a keyword for the person on every image in the person's collection. I imagine one could write an AppleScript plugin for MP that would automatically do this. This will be the only way to insure “People” come over from MP to C1.

IPTC metadata, ratings, keywords come over (save for keywords getting flattened as noted above).