I can’t for the life of me find a way to view the ID of a label. I know the general rule is lower case of name and _ for spaces and special chrs. So you can guess at it some times but its always a guess. Would be nice if in the Settings > Labels that it would tell you the ID in the UI when you click on the label.
The pit you fall into is that the id is generated from the first creation of the label.
Any change in the name of that label after the creation will not change the id.