You have ‘Match Multiple’ selected. Was that intentional? The relation could potentially have multiple matches, so there is no way to know which specific row you want to link to. It needs to be a single relation.
Each deal is it’s own row but relates back to the same business.
I also don’t have to set it up this way, it’s just how I had it before, and it allowed the “view deals” button to only appear when someone actually had a deal available.
Classic apps worked a little differently, where a screen could be connected to an entire table as opposed to a single row. In New apps, each screen needs to be linked to a single row. That’s why you can’t just to a multiple relation…because which row would it be linked to out of many.
I think what you should do instead is set you button action to ‘Show New Screen’ → ‘This Item’ to get a new screen still linked to the same salon. On that new screen add a collection sourced from the relation. That should show all of the promos as a collection.