this is a quote from the FAQ:
"No. Players who are chat or ranked restricted or currently banned from play cannot earn or unlock chests through Champion Mastery. Once they’ve reformed, they’ll be eligible for rewards again."
I am not chat restricted. I hit level 5 mastery on Shyvana and got a message saying I am ineligible for the reward. Plz fix.
This has been reported on another post too, its not that you are restricted, its a bug that you dont always obtain the chest even though you should by the rules. :/ Please upvote the other Hextech Loot Bug post too!
Have the same issue. been chat restricted before for heckling with enemy zed smurf. It's been a week or two since I payed back for my restriction I think but yeah. Can't earn anything so I'm just playing to level
The same thing is happening to me. I admit I've had my days when trolls get to me and I stoop down to their level. However, I do not have any current restrictions on my account and even got a message the other day after a game saying my account is clearing up its mistakes. It's been a little over a month since I was last restricted. Hopefully Rito will fix this. As for now, I get to watch my 5s buddies get crates and keys. feelsbadman 
Wait what exactly is this? and is it active for all champions on NA?
I keep getting this message as well. I had a 10 game chat restriction a week or two ago, so I thought I was just banned from having any rewards from this system.
So is this a bug or if your account has had problems do you not get to participate in this hextech thing?
same, i got a mastery 5 on two champions and no reward... but i seem to be able to still get chests from S matches and key fragments from winning
It's cause you have to prove you've reformed by maintaining good standing in the honors system. No reports for a while and you'll be eligible.
Yeah, I'm also having the same issue, can riot please look into this? I was chat restricted like a month ago I did my 10 game chat restriction.
DITTO!!! I was on Chat restriction (only 10 games) about a month ago so now not getting a Grade or any Loot either. Check out my posting and see if similar. If yes, when please vote to help get attention to the problem. Thanks! Click HERE to go to my related posting
Same, three games now where someone got an S rank and I haven't gotten a single chest from it.
I am not restricted or banned, received an S on Morgana then was given the same chat message about not being awarded a chest due to behavior restrictions. Please fix and distribute the earned chest. Thanks!
I've lost out on 4 rewards now because I am "Ineligible", I'm not chat restricted or anything and this is really annoying. I know that Riot will never grant the rewards that I earned but at least fix this for the future as it is super irritating since you can only receive an award once per champion...
