While we can't provide tax advice and each private investment as its own facts and circumstances, the key is that the investment is not considered active but rather passive. You may want to ask the question to the private placement manager as it comes down to how the LLC reports the returns on the K-1. If it is considered an active investment, meaning they are operating the placement as a business instead of as an investment.
ANSWER:
While I can't provide tax advice and each private investment as its own facts and circumstances, the key is that the solo 401k investment is not considered active but rather passive. You may want to ask the question to the private placement manager as it comes down to how the LLC reports the returns on the K-1. If it is considered an active investment, meaning they are operating the placement as a business instead of as an investment.
Please see more including a podcast we recorded with a UBIT expert who could serve as a resource for you: