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 
* be caed whenever new keys are added to the , with the oldest key
 * creation time.
 *
 * @return Earliest timestamp that could be successfuy scanned from. Timestamp
 * returned wi be higher than startTime if relevant blocks could not be read.
 */
int64_t CWaet::RescanFromTime(int64_t startTime, const WaetRescanReserver& reserver, bool update)
{
    // F
    // h
    // t
    int start_height = 0;
    uint256 start_block;
    bool start = chain().findFirstBlockWithTimeAndHeight(startTime - TIMESTAMP_WINDOW, 0, FoundBlock().hash(start_block).height(start_height));
    WaetLogPrintf("%s: Rescanning last %i blocks\n", __func__, start ? WITH_LOCK(cs_, return GetLastBlockHeight()) - start_height + 1 : 0);
    if (start) {
        // T
        ScanResult result = ScanForWaetTransactions(start_block, start_height, /*ma reserver, /*fUte, /*sae);
        if (result.status == ScanResult::FAILURE) {
            int64_t time_max;
            CHECK_NONFATAL(chain().findBlock(result.last_failed_block, FoundBlock().maxTime(time_max)));
            return time_max + TIMESTAMP_WINDOW + 1;
        }
    }
    return startTime;
}
/**
 * Scan the block chain (starting in start_block) for transactions
 * from or to us.  fUpdate is true, found transactions that already
 * exist in the  wi be updated.