Block Finding issue with RVN.
### Description

Hi there,
I'm currently testing RVN coin. I've increased shareDiff to **55K**
SGMiner shows the difficulty of the submitted share. 
As you can see from the screenshot, One of my rigs submitted **a share with 593K difficulty**
Block diff is around **67K**. The 593K diff share should find a block right? Or is there something that I miss?

### https://imgur.com/a/zkRKMms

### Steps to Reproduce

1. Start MiningCore 
2. Start mining software (SGMiner)
3. Mine RVN and find high diff shares

### Expected behavior

A share with 595K diff should find block.

### Actual behavior

Nothing happens, just accepts share and continues.

### Reproduces how often

Allways

### Version

44

### Additional Information

Config file 

`{
  "logging": {
    "level": "info",
    "enableConsoleLog": true,
    "enableConsoleColors": true,
    "logFile": "miningLog.txt",
    "logBaseDirectory": "",
    "perPoolLogFile": true
  },
  "api": {
    "enabled": true,
    "listenAddress": "127.0.0.1",
    "port": 4000
  },
  "banning": {
    "manager": "integrated",
    "banOnJunkReceive": true,
    "banOnInvalidShares": false
  },
  "notifications": {
    "enabled": false,
    "email": {
      "host": "smtp.example.com",
      "port": 587,
      "user": "user",
      "password": "password",
      "fromAddress": "info@yourpool.org",
      "fromName": "support"
    },
    "admin": {
      "enabled": false,
      "emailAddress": "user@example.com",
      "notifyBlockFound": true
    }
  },
  "persistence": {
    "postgres": {
      "host": "127.0.0.1",
      "port": 6344, ,
      "user": "miningcore",
      "password": "PWD,
      "database": "miningcore"
    }
  },
  "paymentProcessing": {
    "enabled": false,
    "interval": 600,
    "shareRecoveryFile": "recovered-shares.txt"
  },
  "pools": [
    {
      "id": "rvn",
      "enabled": true,
      "coin": "ravencoin",
      "address": "WALLETHERE",
      "rewardRecipients": [
        {
          "address": "WALLETHERE",
          "percentage": 0
        }
      ],
      "blockRefreshInterval": 100,
      "jobRebroadcastTimeout": 10,
      "clientConnectionTimeout": 600,
      "banning": {
        "enabled": true,
        "time": 600,
        "invalidPercent": 50,
        "checkThreshold": 50
      },
      "ports": {
        "16001": {
          "listenAddress": "192.168.1.22",
          "difficulty": 55000,
          "name": "GPU Mining"
        },
        "16002": {
          "listenAddress": "192.168.1.22",
          "difficulty": 55000, 
          "name": "GPU Mining"
        },
        "16010": {
          "listenAddress": "192.168.1.22",
          "difficulty": 55000,
          "name": "GPU Mining"
        }
      },
      "daemons": [
        {
          "host": "127.0.0.1",
          "port": 42068,
          "user": "user1",
          "password": "112233Aa"
        }
      ],
      "paymentProcessing": {
        "enabled": false,
        "minimumPayment": 0.25,
        "minimumPaymentToPaymentId": 1.0,
        "payoutScheme": "PPLNS",
        "payoutSchemeConfig": {
          "factor": 2.0
        }
      }
    }
  ]
}`
