Hi Quintijn!
You could still use this approach from this thread, but honestly I think the simpler way to accomplish getting table records into a single/multi-select is to use a “unique values” aggregation and then use that aggregation as the data source in your single/multi-select. (At the time of this post, “Unique values” was not an aggregation option in the platform, hence why the connector approach here)
To see a walkthrough of how this would work, you can check out John’s post below!
Let me know if this helps, or if you prefer the connector option, we can debug that further.