There is a bug in the conditional formatting options when trying to use "advanced options" in a matrix which shows (distinct count) values as percents of row totals. When conditional formatting is first turned on, it looks as expected. Here you can see the largest values in each row are green, which makes sense.
However, as soon as I click into the "advanced controls" to adjust this formatting, Power BI switches the formatting to percent of grand total, even if I do not change anything in the advanced control settings. There is no option to switch it back. The only way to switch it back is to turn the conditional formatting off and back on again to reset it. Here is what this unexpected result looks like.
In the image below, I have switched my values to display the counts as percents of GRAND total so you can clearly see this is what the app is using in the above image.