I didn’t know about the threshold. i just guessed that small number compared to 5000+ is gonna be a thin line and that’s why anki doesn’t show it (or it’s too thin to see there)
but in the review count number it’s a different story because if he did 155 reviews in one day and 5 of them are mature, it’s gonna be noticeable and that’s why it show mature cards in review count chart and not in answer buttons chart.
but you can check if it actually doesn’t show any mature cards on answer buttons chart by hovering over the chart @jhall_88
(I have hovered over the chart and it shows me the exact number of pressed button / if it’s 0 for you then you can say for sure something is wrong with the stats)