If you want to use a slider as a progress bar or to display values (similar to an analog meter) just follow these instructions:
First, do not assign any action to the slider element. Only assign the corresponding status value as status.
In order to avoid that the slider element remains operable in the app, i.e. it can be used as a slider (because sliding is still possible, even if no action is assigned), open “Advanced Options” in the properties menu and tick the checkbox Disable control.
If the check mark is set, the slider only serves as a display element and the function as a “slider” is inactive.