It’s not uncommon that organizations opt to outsource this task to an external agency. The issue with this is that most agencies come from advertising backgrounds and approach this akin to market research study resulting in a broad demographic study rather than a UX research focused on behavioral patterns. Each project or a service warrants more in-depth look with context being key. As you’ve noticed, demographic data only serves 1/4 of the persona chart, while “Think/Feels” & “Does” quadrants are deeper understanding which can be extracted best with User research.
Personas don’t represent users. They represent users’ goals. If you can’t reduce the number of goals of your user community down to very few, you don’t understand your users, your product, your business, or interaction design.
Share with me the scenario and put a spot-light on it. If you have a question, anecdote or an interesting topic to raise in UX, send them through. Discussing & articulating the challenge would be the 1st step in edging closer to a remedy.