So I created a model-driven app based on this video from Lisa Crosbie (The timestamp is also included there):
https://youtu.be/GbqnAH5m11o?t=28
In this video she showed that when you clicked on a Lookup field, it displays the values without pressing Enter or anything else.
In my solution and app, however, I have also created a lookup with filters (I didn't follow hers exactly since I got the idea and tried to explore on my own). I got the filtering right, including the relationships, but it seems that when I click the Lookup field, it doesn't display anything (Video attached).
How can I display the values from the Lookup fields?