One of the most frustrating things about Knack is that the connections made using form rules are not implemented until after the form has been submitted. In many cases, it makes sense to pull information from the object you are connecting with a form for use in the same interaction.
Currently, the only way around this is to create a 2 stage form that makes the connection upon the first submission and then uses that connection upon the second form submission - This makes for an ugly UI experience.
If Knack were to add a second stage for rules on each form submission, which was implemented after the first batch had already been executed but before the submit rules were executed then builders would be able to use the connections created in the first batch of rules in the second batch of rules without creating a two stage form.
The entire process would be invisible to the app users and their experience would be vastly improved.