in v0.12 https://github.com/bitcoin/bitcoin/pull/7081 (by @luke-jr) was merged adding `-bytespersigop` (with default of 20).

this is preventing simple bare multisig transactions from being accepted into mempool when the size is < 400 bytes.  
eg; https://gist.github.com/rubensayshi/ac4f617207f7a50559e85d61c05800be

from 1-of-7 and onwards they are accepted because the ratio of bytes:sigops is high enough.  
also having 2 or more inputs will work because it again tips the ratio of bytes:sigops over.

the reason mainly being that `GetLegacySigOpCount` calls `GetSigOpCount` with `fAccurate=false`.

It looks like changing `GetLegacySigOpCount` to use `fAccurate=true` would cause side effects in the few other places (`ConnectBlock`, `CheckBlock`, `CreateNewBlock`) and simply adding `fAccurate` as arg to `GetLegacySigOpCount` would affect the value stored in `CTxMemPoolEntry.sigOpCount` which in turn affects a bunch of other things.

{
    LOCK(cs);
    return minerPolicyEstimator->estimateSmartFee(nBlocks, answerFoundAtBlocks, *this);
}
double CTxMemPool::estimatePriority(int nBlocks) const
{
    LOCK(cs);
    return minerPolicyEstimator->estimatePriority(nBlocks);
}
double CTxMemPool::estimateSmartPriority(int nBlocks, int *answerFoundAtBlocks) const
{
    LOCK(cs);
    return minerPolicyEstimator->estimateSmartPriority(nBlocks, answerFoundAtBlocks, *this);
}
bool
CTxMemPool::WriteFeeEstimates(CAutoFile& fileout) const
{
    try {
        LOCK(cs);
        fileout << 109900; 
        fileout << CLIENT_VERSION; 
        minerPolicyEstimator->Write(fileout);
    }
    catch (const std::exception&) {
        LogPrintf("CTxMemPool::WriteFeeEstimates(): unable to write policy estimator data (non-fatal)\n");
        return false;
    }
    return true;
}
bool