The distribution is long term capital gain by the amount that exceeds your partnership basis. Therefore, only the amount of box 19 A that is greater than your adjusted basis in the partnership will be taxed.
It sounds like your capital basis is showing you there was no excess gain. Any excess long term capital gain should be reported in the capital gain boxes (or ordinary income/other as applicable), which it sounds like yours are empty (often box 8-10). See the Schedule K-1 (1065) instructions for box 19:
If the
amount shown as code A exceeds the
adjusted basis of your partnership interest
immediately before the distribution, the
excess is treated as gain from the sale or
exchange of your partnership interest.
Generally, this gain is treated as gain from
the sale of a capital asset and should be
reported on Form 8949 and the Schedule D
for your return. However, if you receive cash
or property in exchange for any part of a
partnership interest, the amount of the
distribution attributable to your share of the
partnership's unrealized receivable or
inventory items results in ordinary income
(see Regulations section 1.751-1(a) and
Sale or Exchange of Partnership Interest,
earlier). For details, see Pub. 541.
Read more at the instructions (page 13):https://www.irs.gov/pub/irs-pdf/i1065sk1.pdf
Let me know if you have any follow up questions.
