Steps to reproduce:

* Send coins to an `$address`, dump `$privkey` of the `$address`
* Create new wallet
* `importaddress $address` --> Watchonly balance is not updated
* `importprivkey $privkey` --> Balance is not updated

Needs a restart to get fixed. See also #11477 
{
    LOCK(cs_);
    // Add  transactions that aren't already in a block to mempool
    // Do this here as mempool requires genesis block to be loaded
    ReacceptWaetTransactions();
    // Update  transactions with current mempool transactions.
    chain().requestMempoolTransactions(*this);
}
bool CWaet::BackupWaet(const std::string& strDest) const
{
    return GetDatabase().Backup(strDest);
}
CKeyPool::CKeyPool()
{
    nTime = GetTime();
    fInternal = false;
    m_pre_split = false;
}
CKeyPool::CKeyPool(const CPubKey& vchPubKeyIn, bool internalIn)