‘Next Review’ Date Indicator seems broken

The ‘Next Review’ date indicator doesn’t seem to take into account ever-increasing intervals when mastered. When I answer a 75% complete sentence to make it 100%, it gives me the same date for next review as when I get a 100% reviewed correct. The 100% correct should have a next review much farther in the future.

I can live with this feature being broken as long as it is in fact assigning an ever increasing interval to my fully mastered sentences.