here's your situation based on your example
you put in 1200
you reported net income over the years on your tax return of 500
you never got any prior distributions
so you should expect 1700 in cash when it was liquidated
put another way. if you put 1200 into a savings account to start
and over the years it earned 500 of interest income
when you closed the account wouldn't you want 1700
that's your situation with the partnership. you should have gotten 1700 of cash
but you only got cash of 1500
200 is missing and it is this other asset that was distributed.
the partnership was supposed to include info about this other asset with the k-1.
that leaves multiple possibilities of which this list is not an exclusive
1) the returns have been prepared incorrectly.
2) the property was sold for $y of which it only received $x in 2021 the rest will be received in the future.
3) the returns have been prepared incorrectly.
4) the asset while having 200 of tax basis is worthless.
5) money was retained for possible unexpected bills, you'll get the balance when these are taken care of
I don't know how much $$$ this other asset represents so it's really up to you as to whether to pursue this matter or not
