Scan_tx stucks on newer versions
It seems because of [this](https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/wallet/wallet2.cpp#L1925-L1927) todo, Scan_tx gets stuck when trying to scan transactions before syncing wallet.

It is related to woodser/monero-ts#212.