@Rowan1 According to the data that @ierazo has collected (look here), there is a ~77% chance of NOT getting a 4* AM in a given chest. The 5-in-a-row streak without 4* that you have had is still a ~27% chance of happening. Bad luck, but not totally statistically unreasonable. Sorry man.
I’ve had a run of 2 in a row without any unfarmable mats at all. There’s only ~10% chance of getting no unfarmable mats and only a 1% chance of getting two of those in a row. Yay me. 