Bitcoin wallet is empty after importing using key phrase

Do you know what happened and if/how I can recover my Bitcoin?

First of all, find out what software you originally used. Was it a desktop/mobile wallet? What was the name of the application you set up your wallet with? Check out this website and check the route column. If your original software wallet supports the following paths: m/0' However, due to a software upgrade, the new version supports the following new paths: m/44'/0'/0' Or it could be a completely different software wallet that supports other routes, such as: m/49'/0'/n' – In these cases, the balance will not be displayed in the new wallet as the addresses are derived differently from different paths.

If you know the address of your old wallet, you can also try the Iancoleman tool. Remember to use it in offline mode. I personally wouldn’t use it for larger amounts anyway.