ProxySQL Instance Summary dashboard: no Node Metrics

Impact on the user:

Troubleshooting of ProxySQL services is complicated because on not full information on the Instance page 

STR

1. Setup PMM
2. add PXC  with proxySQL instance 
3. Add ProxySQL and it's node into  Monitoring by PMM
4. got to /graph/d/proxysql-instance-summary/proxysql-instance-summary  
5. Scroll to bottom
6. open Node Summary section 

Expected result

• All node metrics

Given result 

• the smallest number of metric presendet 

If you go to Node Summary Dashboard - all metrix exists. the problem in formula/parameters on ProxySQL  dashboard