I'm not sleeping because of a possible bug in the wallet blockchain info.
I keep my BTCs in a cold wallet, which I enter the PK in the option of importing addresses from Blockchain.info, and transfer the desired amount to the exchange, moving the rest to another cold wallet that I create with bitaddress, I've been doing this for a while and I've never had problems.
To track the balance, I always enter the public key in blockchain.info (Watch Address), this time I saw that there was a 'Private Key' field on the screen below the Watch Address, allowing me to move my bitcoins right there, without having to import them.
I entered the private key in the field below the public key of Watch Address, put the exchange address and the amount that I want to send, imagining that the change of the partil spend, should go to the main wallet.
https://i.stack.imgur.com/A76xC.pngPK field
However, the balance that was in the paper wallet:
https://blockchain.info/en/address/1AXXCct4QATf2UdX92piw1AA2As8AoZaoM, was moved to change address:
https://blockchain.info/en/address/1KfTVrLG376B7SYb1bA6NnY7KyK825T72B, which had 2 outputs, one for the exchange (1PjcZKMFR8wkFjoMAE2aoVfSeB5xHwVLdu) and another for herself (Change).
https://i.stack.imgur.com/lSVH2.pngOutputs
But, this address does not have a private key (1KfTVrLG376B7SYb1bA6NnY7KyK825T72B), is appearing as Watch Only in Blockchain, I understand that it should be moved to main wallet address containing the change funds.
https://i.stack.imgur.com/TOa8R.pngWatch Only Change Address
I have already tried to use the tool:
https://iancoleman.github.io/bip39/, as described in this post:
https://bitcointalk.org/index.php?topic=2162043.0, which shows all addresses generated by the seed of blockchain.info, I find some of the retroactive outputs of this change, but not the 1KfTVrLG376B7SYb1bA6NnY7KyK825T72B.
I tried to email them through the request page, but I do not think they'll respond there.
The value is low but it's all my savings, thank you for all your help.
