Partial deferral can be intentional.
An investor may choose to receive some cash or other non-like-kind value while completing an exchange with the balance. Federal rules can require recognition of gain to the extent of money or non-like-kind property received, subject to the applicable calculations.
The decision should be modeled rather than guessed. Basis, debt, expenses, closing credits and cash retained can affect the result. A tax professional should calculate the expected recognized gain and replacement basis before the structure is finalized.