I found this website that gives some more “color” on the PFIC question.
https://hodgen.com/is-my-investment-account-a-pfic/
Quoting from this article: “An investment account is not a corporation – it is an account that a financial institution maintains on your behalf. Therefore an investment account cannot be a passive foreign investment company. Your account is not a PFIC.”
It goes on to give some guidance on how to determine a PFIC.
Based on some of the examples (e.g., Nestle), I question whether funds like Rock Capital, BlueCrow and maybe others are perhaps not PFICs. In these cases specifically, they are funds which hold companies who are constructing buildings or farming. In the case of BlueCrow for example, if the two brothers are actually engaged in the work and generating income from farming business - for them it is not passive income.
If the fund is buying bonds, equities or just investing in other companies that are constructing things, then I think it is clearly a PFIC.
If the fund is buying a building and leasing it to a third party for rental income, this is more unclear to me but I suppose it depends on the level of involvement in management and operations of the lease.
Based on this, I believe if a fund believes they are not a PFIC, then they should get a legal opinion from a US tax lawyer that the fund is not a PFIC and this may help to resolve that issue.