It seems that fractal rewards are bugged. According to the post linked below, the rewards for fractals was going to receive a buff. Instead since the release of HoT, I don’t think I’ve even received 1 ring and that is after progressing from level 29 to level 50. In addition, I have mastery level 4.
Seems to be a bug with the loot drops.
https://www.guildwars2.com/en/news/the-guild-wars-2-heart-of-thorns-economy/