I observered this behaviour as follows:
Only Show Member Price checked : variant pricing ignored for member when member selects to apply member sidcount in cart
Only Show Member Prices By Role checked : variant pricing ignored for member (no option to apply member pricing)
Both checked: variant pricing ignored when I opt to receive my discount
I have not added any product member pricing since I only want a single member price, and the member pricing by product seems to require me to enter 2 strings and 2 prices or else I get a " A critical error has occurred. Input string was not in a correct format." error (I suspect this is another bug).
I have set both unit cost and member price to 15
I have added a single checkbox variant with the price adjustment set to 10