No Hextech Chest from S rank

Not sure if this is a repeat report or not, if so sorry.

In a very simple explanation, you exclude all champions that are on free rotation from getting champion mastery due to the nature of players not owning that champion. This directly affects players that actually own the champion and it seems to affect if they will get a chest from a S-Rank game. Mind you all of what I said is an assumption and guess work on how it most likely is coded. If my assumption is correct this might be a oversight on the Hextech crafting system that probably should be fixed as soon as possible. I mean it is very frustrating to have a game where you do really well and the expected reward is nothing but dirty snot.

More information: Yes, I have not acquired all my chests for the month. In fact none, meaning I can get four if I bother to play SR. I consider myself a ARAM main, which is frustrating enough that we have been left in the cold when it comes to Hextech crafting. In an attempt to put that rant aside, I played a normal draft pick SR game with some IRL friends. I managed to get S-rank with Morgana whom is free at the current moment. If it means anything I do own her and a decent amount of her skins, doubt it matters though.

I have never acquired a chest for Morgana, however in stats the chest icon is no longer grayed out and my highest rank acquired is now S. Sorry cannot prove that it was because I wasn't expecting to run into this issue...

I also double checked my inventory when the post-game chat stated I got a S-rank but did not say anything about acquiring a chest. Still zero chests in my inventory. I do believe, not 100% though but I think that my friends might of gotten something from it as we are in the same club. I'll have to ask at a later time as it is quite late in the night.

Here is the match details: LINK

The questions: Is this known as a bug/glitch or possible oversight? Is there a way to get the chest I should have gotten? (I already assume this is a lost cause but it can't hurt to ask)

Thanks for your time, xBLiNDBoi