How do I put the threshold reference line on the X-axis?

[Jhilene]

I am trying to place a threshold line on the x-axis using this query

Perf
| where TimeGenerated > ago(1d) 
| where CounterName == "% Processor Time" 
| summarize avg(CounterValue), percentiles(CounterValue, 50, 95)  by bin(TimeGenerated, 1h)
| extend Threshold = 20

However, it is not giving me the option to have 1 threshold line on the x axis. It's called a "reference line", according to this tutorial: https://docs.microsoft.com/en-us/azure/azure-monitor/log-query/charts

I've attached an image.

[#2]

Anyone? I've been blocked by this all day. No answers anywhere.

[#3]

@Jhilene 

This shows up best with a linechart 

Perf
| where TimeGenerated > ago(1d) 
| where CounterName == "% Processor Time" 
| summarize avg(CounterValue), percentiles(CounterValue, 50, 95)  by bin(TimeGenerated, 1h)
| extend Threshold = 20
| render timechart 

[#4]

@Clive Watson I see it does, but I do not understand how alerts graph is able to do it with a bar graph https://docs.microsoft.com/en-us/azure/azure-monitor/platform/alerts-log