Here is my scenario - I have 2 data connections: one is just a list of Disciplines and Lead people; second is a Contact List (just Names). I also have 2 fields "Discipline" (dropdown list populated with data connection 1 info) and "Lead Person" (dropdown with all "Names").
When Discipline field selected/changed, rule runs that sets "Lead Person" value depending on selected Discipline. I can also change "Lead Person" value by selecting another name from the dropdown. But regardless what is saved, when I run the form, "Lead Person" value changes back as if the "Discipline" field has been changed. I realize that my text is kind of foggy, so here is the example
Sharepoint list has an entry: Discipline = "Administration"; Lead = "John Smith", so when I select "Administration", the Lead dropdown selected value changed to "John Smith"
Then I select another name in the Lead dropdown, let's say "Mary Brown" and click Submit Form. Saved values Discipline = "Administration"; Lead = "Mary Brown"
Then run the form again and after loading I have Discipline = "Administration"; and the Lead is "John Smith"? Why? Looks like the rule runs on Form Load as well