PsychoPy Slider component does not appear offline nor online v2021.2.3

URL of experiment:

Description of the problem: I have designed an experiment with a 9-point-likert scale. The experiment works fine when I use it offline with the rating scale component with custom settings.
I have seen in some forum posts that the rating scale component is not advised for online use on pavlovia.org. Fair enough, I tried it and the rating scale does not appear with the PsychoJS script, as the code for the rating scale is not translated from the Python script to the Java script.

I tried therefore to use the slider component, but with that, I don’t see any rating scale, neither offline nor online. I am using Version 2021.2.3.
Does anyone know why this happens? I tried to just implement the slider component with a new project, but it never appears on the experiment screen and simply gets ignored by the program. When I add other components to the routine, those are ignored as well, i.e. the whole routine is not implemented into the experiment.

If anyone has seen a similar issue and knows a way to solve it, please let me know!
Thanks, Klemens