If you change the mastery values in your page AFTER you've changed it's name, it will immediately revert back. Also, if you change your mastery values and have forgotten to change the master page name which is not unheard of you can't just go back and change the name because the save option won't become available without requiring you to change a mastery value, which resets your name change.

Edit, The resetting issue I mentioned only occurs the first time you change a mastery value after changing the name

Yea I found this a little too late to fix for the patch but I'm working on a fix for this. As far as save not activating when you change the name, it should once you hit enter, just not immediately as you type. If it seems to be confusing we can make it activate sooner. Thanks for the report.