Research into the effective assessment of experienced HR Generalists - balancing technical, behavioural & cultural fit

Please answer the following questions

Please can you limit your answers to hiring HR generalists at a senior specialist (Manager/HRBP) through to Leadership (HR Director, Head, VP etc) in this questionnaire. All results will be completely anonymous, so reflecting your actual experiences will be very welcome. 
1.What do you find most challenging to assess of HR professionals when selecting them for your organisation?
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