This conversation would be more appropriate to the elemental chests thread, but I would say what you’re experiencing is NOT unusual. It isn’t just you; it’s that your mind does not intuitively grasp randomness and the streaks it creates (none of ours really do - we’re all programmed to specifically be BAD at this task).
FWIW, I quickly crunched some of my tracking, and it suggests the following rates:
4* AM: ~13.6%
3* AM (non-farmable): ~54.5%
Crap (by which I mean a farmable 3* AM): ~31.8%
Summon token: ~77%
Hero token: ~15.9%
Troop token: ~12.9%
That’s per roll by the way, NOT per chest. Given those percentages, it is hardly surprising to have a short stretch (and 5 is certainly short in this context) without a 4* AM or EHT.