I developed a program that mints nfts. I added in the UI the possibility of minting more than one nft at once. To accomplish this I create a transaction for each nft that the user wants to mint.
Each transaction has 2 instructions in order to create the nft. Each instruction has 7 and 13 accounts on their context struct. In total, each transaction has 20 accounts.
The multi minting goes fine when minting up to 3 nfts. By fine I mean that my Phantom wallet shows the total price of all the minting, I approve the transactions and the nfts are minted correctly.
But when I try to mint more than 3 nfts at once, lets say 4, my Phantom wallet shows the error "Unable to fetch balance changes". For my surprise, if I approve this transaction despite the error message, the nfts are created succesfully, all 4 transactions succeed on-chain. I can mint lets say 10 nfts at once and the transactions on-chain are completed but Phantom shows the error and not the transaction price.
Any suggestions on this? Thank you.