I am using Koinly for NFT taxes. There appears to be a systematic koinly BUG in that if you accepted an offer for .1 WETH to buy an NFT, koinly does NOT recognize that as a “trade”, but rather as 2 separate transactions, where you “sent” .1WETH and “received” an NFT. As a consequence, the cost basis of NFT is recognized as ZERO (as opposed to correct .1ETH), which DRAMATICALLY overstates taxes. Is there a way to fix this issue. This is a HUGE problem since it leads to systematic tax overpayment as true cost basis is understated.
To fix an NFT purchase, you just need to locate the withdrawal of the spent coins in your wallet and merge it with the NFT deposit. These transactions will usually have the same timestamp and transaction hash so they are easy to identify.
Merging the transaction will create a single trade and Koinly will then be able to calculate the cost-basis of the NFT.
For more information on this, please see this article.