On the Android app, I've recently come across two obstructing bugs in Quick Draw:
Suddenly, the mode I chose did not reflect upon the actual mode given: I selected slowly disappear after playing a round of hints only, but after re-selecting multiple times, I still wasn't able to successfully change the mode.
I randomly, often get told I changed the mode mid-game (I hadnt touched the mode buttons mid-game, and was playing the same mode every kana) and that my data would not be saved.
After restarting, the latter wasn't fixed, only when I pressed "Start over again" (I was pressing Return to menu before), did the mode I picked work.
Edit: Now the first bug has a 100% replication rate, no data in Quick Draw gets saved. I will try switching devices/clearing cache when I am home.
Getting this same problem this last few days, sometimes it works fine and other times I get to the end and this comes up. I am not using an app but I am on an Android phone.