TaxJesus' solution worked for me (no increase in refund though).
All I did was open the Schedule K-1 form, scroll down to Section D1 (entitled "Qualified Business Income Deduction - Statement A Information"), and fill in the first table there. Just above the table is a line saying, "Shareholder's share of QBI or qualified PTP items subject to shareholder specific determinations". In my case, I simply needed to supply a number for "Ordinary business income (loss)" in the first line of the table, which I took as the value of Box 1 in Part 3 earlier in the Schedule. Re-ran TurboTax check, and it passed! My refund went up a bit too.
