K-1 should come with a multi page instruction sheet https://www.irs.gov/pub/irs-pdf/i1065sk1.pdf
From that you would find:
• Net short-term capital gain (loss) and net
long-term capital gain (loss) from
Schedule D (Form 1065) that isn't portfolio
income. An example is gain or loss from the
disposition of nondepreciable personal
property used in a trade or business activity
of the partnership. Report total net short-term
gain (loss) on Schedule D (Form 1040 or
1040-SR), line 5. Report the total net
long-term gain (loss) on Schedule D (Form
1040 or 1040-SR), line 12.
I believe that confirms you inclination to just include it with line 9a.
I believe that will throw it into being subject to net investment income.