[Client/Gameplay?] Unable to Save Changes to Masteries.

I've noticed a few times now after trying to use certain mastery pages, they appear as 0/0/0 pages. I edit them, save them, and then in-game it shows that I have no masteries. My friends have joked around and insist that I frequently don't save changes to my masteries pages. Irritated, I changed them again and saved even when I wasn't planning on using the page that game.

I just had it happen again, where I made changes in lobby, saved with plenty of time to spare, and loaded in without any masteries being applied. After the game, I go to "My Collection" where the 2 affected Masteries pages appear as 0/0/0 and have a red "!" next to them. I have tried numerous times to make changes to them and save, only to come back to the collection to find that they are 0/0/0 again.

I have tried deleting the pages, and upon returning to "My Collection," I find that they have returned, and are still 0/0/0. It seems that I am unable to create, delete, or edit any of my masteries pages, even though attempting to do so always appears to work at first. Joining a lobby, loading into a game, and returning to "My Collection" after making (and saving) changes always recreates these pages if deleted, and reverts them to 0/0/0 if edited.

Now I am realizing that creating, editing, renaming, deleting ANY Mastery pages, doesn't work.