Master Tier should be working now.
Please note that not every Summoner has been updated, and may still show in Diamond tier at the moment.
You may also notice that there is no Master tier emblem. That should be coming soon, and the stats will be updated soon to properly display Master.
With the new Master tier, I need to make a few changes to the site for it to work as intended. It should not be difficult, but once the change is pushed live it is possible you might notice some strange behavior with Diamond and Challenger players. Any of these issues should be short lived, but I figured I would give a heads up.
I am expecting to get those changes up within the next day or two.
I've released a few API fixes, so if you've seen slow or no updating in the past few days, that should be resolved.
I still have a ton of things in the pipeline that I'd like to get finished and released, but I've been absolutely swamped lately and haven't had an opportunity to get those things finished up. I hope to have time this weekend to get these changes finally pushed out.