Beef Short ribs still chewy after internal temperature reach 201F [duplicate]

so i currently start to cook beef short ribs on a vertical smoker.

The short ribs i used comes from australian company called hardwicks.

I cook the ribs at 250-285F. Vent are fully opened. Weather is sunny. I marinade them on sweet soy sauce overnight. I use black pepper, cumin powder, paprika powder, onion powder, garlic powder, and sea salt. I spritz them when it reaches 170, and when it hits 190, i wrap it on alumunium foil with some spritz. After hitting 201F i take it out, rest it for an hour, but instead of being butter-like texture, it still chewy.

I don't know how long i cook, i jjst focused on the internal temperature itself.

So does anyone know why it still chewy and not butter-like when it cutted? Thanks everyone, sorry bcs english is not my first language. Cheers!