This is an issue with WordPress rather than iMember360, but luckily it's very simple to solve.
The problem is that there too many columns to be displayed in the listing. Since the listing is "responsive", it tries to adjust the display to accomodate all columns, sometimes resulting in a less than optimal result.
At the top right corner of the listing page, please click on "Screen Options". You will then see a list of columns. You can chose which columns you want to display or not by checking or unchecking the checkboxes next to each column name.
This will quickly solve the issue. Please remember this as you add other themes and plugins, because the number of columns can increase (for example, Yoast SEO) and you may have to use this feature again.