You have a point thereUltra instinct was something even Beerus had trouble mastering if anybody remembers from super where they mention something about it. Mastered MUI Goku I could think possibly would evade the attacks. I'm still not totally sure since we didn't see a lot about MUI Goku yet.
AgreedAs for now, we have to wait if we see more of MUI in Dragonball heroes or if they decide to release something new to it. I am interested to see if there something more behind it and make the fight more clear.
If we going by dragon ball hero’s ss4 vegito and cumber looked more evenly matched then UI goku and cumber. And ssb vegito fought zamasu and that looked pretty close. Jiren looks like he beat zamasu up. he heal then zamasu said it was his turn, but the next cut scene you see him beat up even more and jiren still didn’t have a mark on him lol but the crazy thing is I don’t think that was full power jiren the one that fought UI goku in the tourney of power. So if that was the case UI goku might got this oneAs for now, we have to wait if we see more of MUI in Dragonball heroes or if they decide to release something new to it. I am interested to see if there something more behind it and make the fight more clear.