Thanks for the question. Honestly, I have not yet done much testing with multi-site, but I don’t see why it wouldn’t work. Multi-site does not change any meta functions, so ACF PRO should work just fine.
Currently, ACF PRO requires a DB upgrade from ACF v4. This upgrade will only run on the current website (no multi-site compatibility yet). You will need to login to each sub site and run the DB upgrade prompt.
That should be it!
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