Earning Chests and Mastery Tokens in Limited Feature Games

Scenario/quick question for the more knowledgeable community:

Just today in Hexakill I played MF (already at Mastery lvl 5) and won the match with my team. I earned a "S" rank. I did not receive a Mastery token or a Hextech Chest. In fact this has happened a couple of times, similar scenarios. I haven't been able to earn either reward, despite meeting what I thought were the requirements.

I know the Limited Feature games allow you to earn points toward your lvl 5 Mastery, but are the rewards only earnable in Rift?

Thanks for your help!