Flow Variables Not Displaying In The Dynamic Content Menu

I was trying to dynamically set a SharePoint list item ID to a variable but the variable was not displaying in the Dynamic Content menu.

The solution was to use an expression to set the value, save the flow, exit the edit screen, then re-enter the edit screen.

variables('varRefID')
Create a variable
Notice the variable is not available for selection
Use the expression window to enter the variable name
The variable has been added but looks weird. This is not an issue but continue reading if you want to clean display value.
Save your flow and exit the edit screen.
Edit your flow
The variable is now displayed correctly!