Views Grouped by *each* value of a content field (multivalue).
Grouping is done by the information you have in your results. 

Fields with multiple values return results differently, depending on the Multiple field settings you set on them. 

If you choose to Display all values in the same row then each node will show all "Research Areas" related to it, and if you enable grouping groups will reflect the option combinations from results. This is your current behavior. 

If you untick the option Display all values in the same row each node will be displayed in a separate row showing only one "Research area" it belongs to, but it will be listed as many times as it has "Research areas" attached to it. When you enable grouping in this scenario each "Research area" option will behave "independently". 

So to achieve your desired behavior you need to untick the option Display all values in the same row on your "Research Areas" Field (mind you this is under Fields, and not under Format where Grouping options are).