b) that something beyond the standard model is happening, as in your second and third points.
There’s a failed “prediction” that all fermions have similar mass terms, and that failure suggests either something strange (undetectable particles), something strange (fermions without consistent mass mechanisms) or something strange (novel physics).
"either something strange (undetectable particles)" There is nothing strange here. Undetectable in this context means it would be only detectable by gravitation detectors - all masses/energies have gravitation changes.
We know that either:
a) there’s mysterious undetectable particles, or
b) that something beyond the standard model is happening, as in your second and third points.
There’s a failed “prediction” that all fermions have similar mass terms, and that failure suggests either something strange (undetectable particles), something strange (fermions without consistent mass mechanisms) or something strange (novel physics).
I think that qualifies as a mystery.