Save edited mastery page at the end of count down does not work

Dear Riot,

See image: https://ibb.co/djxk9yr.

It was a time crunch but from my point of view, I finished selecting all the masteries that I wish to take. I believe I even clicked the save button when the window is closed as the game was about to start.

Either way, it completely ignored all my edits and gave me a random mastery page. I got the glacial augment, basically, support preset mastery page for Tryndamere.

There are so many things wrong here:

1. Why would an AD champion get the glacial mastery page as a random?
2. Why can't the game just save the masteries I selected? I would rather have half of my mastery page (and leave the other half blank) than having a random one that has no synergy with the champion.
3. The game has a prompt that asks if I would like to save the page when it closes, please make it actually work. If the page is incomplete, see number 2 above. Or at least randomize only the ones that didn't get picked and let me keep the categories that I selected (precision, domination, etc.).

Thanks!

FQVBSina