I also seem to be having this issue
I created a "raiding" roster and set my DKP system to use it. The settings are getting saved and it says its reading the "raiding" roster but the Current Standings page has not changed. I gave it a day or two to see if the maintenance would fix it but it has not.
Ive tried resaving the DKP settings multiple times as well as having an admin (and no admin) for the "raiding" roster. All the settings appear to be correct but I might have done something wrong. FYI I used the Quick Add to create this roster. I've hit recalculate on the current standings page and its still showing the old list.